# The outdoors, measured.

Rivers and mountains, animals and eclipses, earthquakes and waterfalls. Each work starts from one question about nature and follows it through the data to the end.

## Start here

- [Where was your town 100 million years ago?](https://mariuscomper.uk/unde-era-orasul-tau/en/) — Pick a Romanian place and wind time back 250 million years. The ground under Bucharest lay 760 to 1,650 km further south, depending on which of three published models you use, and Romania rode on blocks that moved separately.

## Masterpieces

Six works chosen for visual power, depth and finish: maps, atlases and stories showing everything this page can do.

- [A drop in the Danube: source to Black Sea in about 32 days](https://mariuscomper.uk/picatura-din-dunare/en/) — About a month in an average year: three weeks in flood, two months in drought. Send a drop down the Danube, from the Black Forest to Sulina, on a clock built from measured current speeds.
- [The dinosaurs of Romania: Hațeg Island, to scale](https://mariuscomper.uk/dinozaurii-romaniei/en/) — Seventy million years ago Hațeg was an island. A fully grown long-necked dinosaur there weighed under a tonne, and a reptile with 10–12 metre wings flew overhead. Stand next to them, to scale, and see on the map where the bones came from.
- [The northern lights have been seen from Romania. How many times since records began?](https://mariuscomper.uk/aurora-din-romania/en/) — Three times in three years: November 2023, May 2024, January 2026. Since 1932, 23 storms have reached Kp 9.
- [The cave bear: the half-tonne giant that ate only plants](https://mariuscomper.uk/ursul-din-pestera/en/) — Males weighed 400–500 kilograms and stood 1.7 metres at the shoulder, and their bones say they ate only plants. Stand next to them, to scale, and see what researchers found in Bears' Cave and three other Romanian caves.
- [The Black Sea has two floors. Nothing downstairs breathes oxygen](https://mariuscomper.uk/marea-neagra-doua-etaje/en/) — The top 50 metres hold oxygen. Below 100–150 metres there is none at all, and the oxygen-free water preserves wooden ships for thousands of years. Dive past the ships, down to 2,212 metres.
- [Elephants, mammoths and deinotheres in Romania: what was found in your county](https://mariuscomper.uk/elefanti-in-romania/en/) — Bones, teeth and tusks of mammoths, mastodons and deinotheres have been found in 23 of the 41 counties. Pick yours, stand next to them to scale, and read what the original paper actually says about the skeleton in the Antipa museum's atrium.

## Selected

- [The cloud above you weighs as much as 80 elephants](https://mariuscomper.uk/cat-cantareste-un-nor/en/) — An ordinary summer cloud gathers about 500 tonnes of water, as much as 80 bull elephants, and still does not fall. Weigh your own cloud, with your own weight on the scales, and learn what holds it up.
- [Are you wider than a stork?](https://mariuscomper.uk/anvergura-ta/en/) — Stretch your arms sideways: that is about how wide you are. Compare yourself, to scale, with 11 birds of Romania, from sparrow to Dalmatian pelican, and learn why the heaviest flier is the bustard, not the swan.
- [Which animals would beat you over 100 metres?](https://mariuscomper.uk/cine-te-intrece/en/) — Pick your age and race 100 metres against the cheetah, horse, dog, ostrich, pronghorn, elephant and hen. The times come from measured races and studies, and over a kilometre you beat the cheetah.
- [Nine seconds between the flash and the thunder. How far away was it?](https://mariuscomper.uk/cat-de-departe-a-fost-fulgerul/en/) — Divide the seconds by three for kilometres, and heard thunder means the storm can strike. With a map of your town.
- [A poppy is red to you. To a bee it is something else](https://mariuscomper.uk/ce-vede-o-albina/en/) — A bee sees ultraviolet, blue and green, but no red. The red poppy looks ultraviolet to her. Look at six flowers through her eyes.
- [When will the sky go dark at noon over your town?](https://mariuscomper.uk/eclipsele-tale/en/) — Pick the nearest town and see every solar eclipse it gets from 1900 to 2100: which were total, how much Sun was left each time, and when the next shadow comes.

## Themes

Each shelf shows the theme's four finest works, hand-picked. Open any shelf to see the full list in the library.

### Romania's nature

Bisons and Danube, earthquakes and cyanide: the country's nature in numbers.

- [The bison comeback](https://mariuscomper.uk/zimbrii-din-carpati/en/) — The last bison of Romania were killed in 1790, and the world's last wild bison in 1927. From 54 animals left in captivity the species recovered, and in May 2026 more than 250 bison lived free in the Țarcu Mountains. Four herds on the map, with dated numbers.
- [Chernobyl over Romania](https://mariuscomper.uk/cernobil-deasupra-romaniei/en/) — 29 April–27 May 1986: the cloud, the readings, the rules — and four days of silence.
- [The spring the water came](https://mariuscomper.uk/inundatiile-din-1970/en/) — The rain, the drowned counties, the rebuild — and the dead have no single number.
- [Thirty centimetres of cyanide](https://mariuscomper.uk/cianura-de-la-baia-mare/en/) — One hundred thousand cubic metres, 2,000 kilometres, four weeks of plume.

[See all 47](https://mariuscomper.uk/en/projects/?subject=earth&topic=romania)

### Atlases and maps

Danube and waterfalls, caves and old trees, on a map.

- [A drop in the Danube: source to Black Sea in about 32 days](https://mariuscomper.uk/picatura-din-dunare/en/) — About a month in an average year: three weeks in flood, two months in drought. Send a drop down the Danube, from the Black Forest to Sulina, on a clock built from measured current speeds.
- [Romania's Tallest Waterfalls](https://mariuscomper.uk/cele-mai-inalte-cascade-romania/en/) — Compare total drop, tallest tier and free-fall for the waterfalls with the greatest reported heights, with the sources and uncertainties of each measurement.
- [Romania has 11 UNESCO sites. The map shows 323 places.](https://mariuscomper.uk/harta-unesco/en/) — A map of Romania's UNESCO World Heritage brings together all 11 sites and their 323 places, with inscription year, criteria, area and conservation status.
- [The “Old Man of the Carpathians” is 900 years old in the papers and about 560 by radiocarbon dating. The oldest dated oak in Romania stands 190 kilometres to the north.](https://mariuscomper.uk/cei-mai-batrani-arbori/en/) — A map of Romania's oldest trees: 5,703 measured ancient trees with species, girth, county and indicative age, the four radiocarbon-dated oaks, and the centuries-old tree nearest to you.

[See all 41](https://mariuscomper.uk/en/projects/?subject=earth&format=atlases)

### Models and deep time

Vanished cities, dinosaurs, auroras and elephants: nature simulated.

- [Where was your town 100 million years ago?](https://mariuscomper.uk/unde-era-orasul-tau/en/) — Pick a Romanian place and wind time back 250 million years. The ground under Bucharest lay 760 to 1,650 km further south, depending on which of three published models you use, and Romania rode on blocks that moved separately.
- [The dinosaurs of Romania: Hațeg Island, to scale](https://mariuscomper.uk/dinozaurii-romaniei/en/) — Seventy million years ago Hațeg was an island. A fully grown long-necked dinosaur there weighed under a tonne, and a reptile with 10–12 metre wings flew overhead. Stand next to them, to scale, and see on the map where the bones came from.
- [The northern lights have been seen from Romania. How many times since records began?](https://mariuscomper.uk/aurora-din-romania/en/) — Three times in three years: November 2023, May 2024, January 2026. Since 1932, 23 storms have reached Kp 9.
- [Elephants, mammoths and deinotheres in Romania: what was found in your county](https://mariuscomper.uk/elefanti-in-romania/en/) — Bones, teeth and tusks of mammoths, mastodons and deinotheres have been found in 23 of the 41 counties. Pick yours, stand next to them to scale, and read what the original paper actually says about the skeleton in the Antipa museum's atrium.

[See all 50](https://mariuscomper.uk/en/projects/?subject=earth&format=models)

### In the field

Delta and caves, Transfăgărășan and salt mines: where to go and what it costs.

- [Danube Delta: ARBDD permits, Navrom Tulcea–Sulina timetables, 2026 fares](https://mariuscomper.uk/delta-dunarii/en/) — The Delta access permit (5/15/30 lei), car, boat, fishing and photo permits, plus Navrom timetables from Tulcea to Sulina, Sfântu Gheorghe and Mila 23.
- [Show caves Romania: Ialomita, Polovragi, Comarnic — 2026 fares and hours](https://mariuscomper.uk/pesteri/en/) — Three caves with official fares: Ialomita (30 lei, all year), Polovragi (20 lei, daily), Comarnic (35 lei, Apr–Oct, min group 5). Hours and measured drives.
- [Transfagarasan: Is It Open? Season Dates, Transalpina Too](https://mariuscomper.uk/transfagarasan/en/) — Is the Transfagarasan open now? Opening and closing dates 2015–2026, Transalpina comparison, altitude profile, fuel, the Balea cable car, and what to do when it's closed.
- [Romania Salt Mines: Turda, Praid, Slanic or Cacica? Prices, Hours, Verdict](https://mariuscomper.uk/saline/en/) — Which Romanian salt mine is worth it? 2026 prices and hours for Turda, Praid, Slanic Prahova and Cacica, depth, temperature, what's inside each, and a verdict per traveler. Praid is temporarily closed.

[See all 15](https://mariuscomper.uk/en/projects/?subject=earth&format=guides)

### Environment investigations

Water, tonnes, earthquakes and quotas: files with figures.

- [Where tap water comes from in Romania’s major cities](https://mariuscomper.uk/de-unde-vine-apa/en/) — Interactive investigation of drinking water origins across Romania’s 10 major cities: surface reservoirs, karst aquifers, 100+ km aqueducts, hardness, and glass chemistry.
- [After the last tonne](https://mariuscomper.uk/dupa-ultima-tona/en/) — What must keep working after a mine closes: the water route, the services requested and what remains unknown beyond the notices’ 48-month horizon.
- [Day Three After the Earthquake](https://ziua-a-treia.mariuscomper.uk/en/) — Bucharest has plans and named institutions for the first 72 hours. After that, responsibility for recovery becomes hard to locate.
- [How Does a Quota Stop? — L43/2026 file](https://mariuscomper.uk/ce-a-respins-parlamentul/en/) — A source-linked file on L43/2026: bear intervention levels, the parliamentary route, and the controls proposed for identification, counting, blocking and alerts.

[See all 7](https://mariuscomper.uk/en/projects/?subject=earth&format=investigations)

## Approaches

The numbers show how many nature works each approach holds.

- [Simulations & models (50)](https://mariuscomper.uk/en/projects/?subject=earth&format=models)
- [Maps & data atlases (41)](https://mariuscomper.uk/en/projects/?subject=earth&format=atlases)
- [Articles & explanations (26)](https://mariuscomper.uk/en/projects/?subject=earth&format=articles)
- [Guides & tools (15)](https://mariuscomper.uk/en/projects/?subject=earth&format=guides)
- [Investigations & audits (7)](https://mariuscomper.uk/en/projects/?subject=earth&format=investigations)
- [Games & tests (2)](https://mariuscomper.uk/en/projects/?subject=earth&format=games)

## All 141 works, newest first.

- [Nine seconds between the flash and the thunder. How far away was it?](https://mariuscomper.uk/cat-de-departe-a-fost-fulgerul/en/) — Divide the seconds by three for kilometres, and heard thunder means the storm can strike. With a map of your town.
- [A five-centimetre butterfly. A migration of up to 15,000 kilometres. No generation sees the whole journey.](https://mariuscomper.uk/fluturele-din-africa/en/) — The painted lady links Europe to Africa in a relay of 8–10 generations: the month-by-month yearly map, the Atlantic crossing, true-size calibration and the Romanian data.
- [What does the water at Herculane taste like?](https://mariuscomper.uk/apa-de-la-herculane/en/) — The same hydrothermal system for two millennia — but different waters spring by spring: Hercules without hydrogen sulphide, Neptun and Decebal strongly sulphurous. Two Roman stones, a 1773 analysis, and the modern lab.
- [Megalodon: how big the biggest shark really was](https://mariuscomper.uk/megalodon/en/) — A megalodon backbone found in Belgium is about 11 metres long on its own. With head and tail the shark was 16.4 metres, and slimmer than a giant great white. Let it swim past you at true scale, see its tooth at real size, and the teeth found in Transylvania.
- [What lives in a drop of water?](https://mariuscomper.uk/lumea-dintr-un-strop/en/) — Zoom into five microscope photographs and try to tell a single cell from a colony or an animal. Discover branching algae and an almost transparent rotifer.
- [Creatures that should not exist](https://mariuscomper.uk/creaturi-ciudate/en/) — Seven Romanian animals that defy biology — from the eyeless king of Movile Cave to the predator that grew 15-fold in 17 years — on a living map, with a quiz.
- [The northern lights have been seen from Romania. How many times since records began?](https://mariuscomper.uk/aurora-din-romania/en/) — Three times in three years: November 2023, May 2024, January 2026. Since 1932, 23 storms have reached Kp 9.
- [Three mammals live in the Black Sea. The seal is gone](https://mariuscomper.uk/delfinii-marii-negre/en/) — The common dolphin, the bottlenose dolphin and the porpoise — about 225,000 of them all, by the 2019 aerial count. Hunting killed millions.
- [A poppy is red to you. To a bee it is something else](https://mariuscomper.uk/ce-vede-o-albina/en/) — A bee sees ultraviolet, blue and green, but no red. The red poppy looks ultraviolet to her. Look at six flowers through her eyes.
- [The Black Sea has two floors. Nothing downstairs breathes oxygen](https://mariuscomper.uk/marea-neagra-doua-etaje/en/) — The top 50 metres hold oxygen. Below 100–150 metres there is none at all, and the oxygen-free water preserves wooden ships for thousands of years. Dive past the ships, down to 2,212 metres.
- [The Plough didn't look like this 100,000 years ago](https://mariuscomper.uk/cerul-de-acum-100000-de-ani/en/) — 100,000 years ago the Plough's bowl gaped almost twice as wide. Drag time across the sky, watch Polaris lose the pole, and meet the people who looked up then.
- [The cloud above you weighs as much as 80 elephants](https://mariuscomper.uk/cat-cantareste-un-nor/en/) — An ordinary summer cloud gathers about 500 tonnes of water, as much as 80 bull elephants, and still does not fall. Weigh your own cloud, with your own weight on the scales, and learn what holds it up.
- [A drop in the Danube: source to Black Sea in about 32 days](https://mariuscomper.uk/picatura-din-dunare/en/) — About a month in an average year: three weeks in flood, two months in drought. Send a drop down the Danube, from the Black Forest to Sulina, on a clock built from measured current speeds.
- [The storks that leave: how Romania's storks reach Africa](https://mariuscomper.uk/berzele-care-pleaca/en/) — A stork from Russia, one from Poland and one from Germany carried a GPS transmitter for a whole year. One reached South Africa, one flew over Brașov, one stopped in Morocco. Follow their road on the map, day by day, then play true-or-false.
- [He hid a number that would not fit](https://mariuscomper.uk/meridianul-care-a-facut-metrul/en/) — The metre came out of a 1,075-kilometre line measured tower by tower between Dunkirk and Barcelona, through the years of war and the Terror. At the southern end Pierre Méchain read the latitude from two places less than two kilometres apart and got two different answers. Follow the chain of 96 stations, drawn from Delambre's own printed table.
- [When will the sky go dark at noon over your town?](https://mariuscomper.uk/eclipsele-tale/en/) — Pick the nearest town and see every solar eclipse it gets from 1900 to 2100: which were total, how much Sun was left each time, and when the next shadow comes.
- [The Mociu stone rain, 3 February 1882: the map, the stones, the museums](https://mariuscomper.uk/ploaia-de-pietre/en/) — One Friday in February 1882, a fireball broke into thousands of pieces above a few villages in Cluj, and the stones came down on snow. The fall map drawn in 1882, the stones set to scale beside your hand and the museums where they sit today, plus the true reckoning of the biggest stone.
- [The Berca mud volcanoes: why they are not volcanoes](https://mariuscomper.uk/vulcanii-care-nu-sunt-vulcani/en/) — At Pâclele, cones a few metres high spit cold mud pushed by methane from 3,000 metres down. No magma, no lava. Stand beside a cone, to scale, and see where the ground really burns.
- [Can you get DNA out of a beetle trapped in amber?](https://mariuscomper.uk/ambra-de-la-colti/en/) — At Colți, in Buzău, people dig amber with insects millions of years old out of the ground. Their DNA has long been gone, and the amber itself is Baltic amber's cousin. Drag the clock back and play eight questions.
- [The cave bear: the half-tonne giant that ate only plants](https://mariuscomper.uk/ursul-din-pestera/en/) — Males weighed 400–500 kilograms and stood 1.7 metres at the shoulder, and their bones say they ate only plants. Stand next to them, to scale, and see what researchers found in Bears' Cave and three other Romanian caves.
- [Which animals would beat you over 100 metres?](https://mariuscomper.uk/cine-te-intrece/en/) — Pick your age and race 100 metres against the cheetah, horse, dog, ostrich, pronghorn, elephant and hen. The times come from measured races and studies, and over a kilometre you beat the cheetah.
- [Are you wider than a stork?](https://mariuscomper.uk/anvergura-ta/en/) — Stretch your arms sideways: that is about how wide you are. Compare yourself, to scale, with 11 birds of Romania, from sparrow to Dalmatian pelican, and learn why the heaviest flier is the bustard, not the swan.
- [How old is sunlight: 8 minutes across space, 170,000 years inside the Sun](https://mariuscomper.uk/lumina-veche-de-100000-de-ani/en/) — Light flies eight minutes to reach you, but its energy wandered inside the Sun for 170,000 years. A random-walk simulation, a race with a neutrino, and eight true-or-false sentences.
- [Why the leaf turns red: three pigments, one short day](https://mariuscomper.uk/de-ce-se-face-frunza-rosie/en/) — The leaf's yellow was there all year, hidden under green. The leaf manufactures the red in autumn, and short days give the starting signal, not the first frost. Mix the pigments yourself, see how much light Bucharest loses, and play eight true-or-false statements.
- [No two snowflakes alike? The 1988 pair and how a flake grows](https://mariuscomper.uk/nu-exista-doi-fulgi-la-fel/en/) — The saying is almost true: two large stellar flakes, alike down to the smallest detail, have never been found. But one pair entered the record books in 1988. Grow your own flake from two settings and count how many fall on your street.
- [The water bear survived open space. A 37-degree day kills it](https://mariuscomper.uk/ursul-de-apa/en/) — Dried out, the water bear spent ten days in the vacuum of space and woke after over 30 years frozen. Awake, it dies at 37 degrees. Measure yourself against it, to scale, and play with its limits.
- [What a raindrop looks like: sphere, bun, mid-air breakup](https://mariuscomper.uk/cum-arata-o-picatura-de-ploaie/en/) — No raindrop looks like a teardrop: small it is a sphere, large a flattened bun falling at 31 km/h, and the giants break up in mid-air. Pick a diameter, see the shape and speed, then play eight true-or-false sentences.
- [Chernobyl over Romania](https://mariuscomper.uk/cernobil-deasupra-romaniei/en/) — 29 April–27 May 1986: the cloud, the readings, the rules — and four days of silence.
- [The spring the water came](https://mariuscomper.uk/inundatiile-din-1970/en/) — The rain, the drowned counties, the rebuild — and the dead have no single number.
- [The bison comeback](https://mariuscomper.uk/zimbrii-din-carpati/en/) — The last bison of Romania were killed in 1790, and the world's last wild bison in 1927. From 54 animals left in captivity the species recovered, and in May 2026 more than 250 bison lived free in the Țarcu Mountains. Four herds on the map, with dated numbers.
- [Thirty centimetres of cyanide](https://mariuscomper.uk/cianura-de-la-baia-mare/en/) — One hundred thousand cubic metres, 2,000 kilometres, four weeks of plume.
- [Ciomadul, Romania’s “extinct” volcano, to scale](https://mariuscomper.uk/ultimul-vulcan/en/) — Ciomadul last erupted 27,000–32,000 years ago, and “extinct” only means 10,000 quiet years. Put the crater, the lake and your own town on one scale drawing, descend to the partly molten rock and see who says what about the volcano.
- [The canal dug twice](https://mariuscomper.uk/canalul-dunare-marea-neagra/en/) — Once with prisoners, once with engineers — and the first dig's dead have no single number.
- [The black snow of Copșa Mică](https://mariuscomper.uk/copsa-mica/en/) — Two works made Copșa Mică Europe's most polluted town: soot, lead in air, soil and children's blood. The figures, from the studies, plus the plume map and the lab bench.
- [The cave that lives without the sun](https://mariuscomper.uk/pestera-movile/en/) — Under a field near Mangalia, a cave with no natural entrance feeds 52 invertebrate species on sulfur and methane, sealed for 2.5 million years.
- [The night Bucharest fell down](https://mariuscomper.uk/cutremurul-din-1977/en/) — 4 March 1977, 21:22: 56 seconds, 32 fallen buildings, 1,578 dead. The map of the night street by street, the ledger of the blocks and the engineer's board that condemns or spares.
- [Elephants, mammoths and deinotheres in Romania: what was found in your county](https://mariuscomper.uk/elefanti-in-romania/en/) — Bones, teeth and tusks of mammoths, mastodons and deinotheres have been found in 23 of the 41 counties. Pick yours, stand next to them to scale, and read what the original paper actually says about the skeleton in the Antipa museum's atrium.
- [A blue whale’s heart can beat twice a minute](https://mariuscomper.uk/inima-balenei/en/) — The heart preserved in Toronto was weighed at 175 kg and is about a metre across, far less than the car it is said to match. Stand beside it, put your hand in its aorta and hear it beat, from 2 a minute in a dive to 37 at the surface.
- [Oase 1: a Neanderthal ancestor 4–6 generations back](https://mariuscomper.uk/pestera-cu-oase/en/) — The remains of a man from about 40,000 years ago, found near Anina: 6–9% Neanderthal DNA from an ancestor 4–6 generations back. The Oase 1 genome, published in 2015.
- [Scărișoara ice cave: ice at least 10,500 years old](https://mariuscomper.uk/ghetarul-de-la-scarisoara/en/) — A 1980 guidebook popularised 3,500 years; the 2017 research puts the minimum age at about 10,500. Map, cold trap, chronology.
- [Where was your town 100 million years ago?](https://mariuscomper.uk/unde-era-orasul-tau/en/) — Pick a Romanian place and wind time back 250 million years. The ground under Bucharest lay 760 to 1,650 km further south, depending on which of three published models you use, and Romania rode on blocks that moved separately.
- [The dinosaurs of Romania: Hațeg Island, to scale](https://mariuscomper.uk/dinozaurii-romaniei/en/) — Seventy million years ago Hațeg was an island. A fully grown long-necked dinosaur there weighed under a tonne, and a reptile with 10–12 metre wings flew overhead. Stand next to them, to scale, and see on the map where the bones came from.
- [PAP 21, PP 5, C/PAP 84 on your packaging — what each one means](https://mariuscomper.uk/coduri-reciclare-ambalaje/en/) — Type the code on your packaging — PAP 21, PP 5, C/PAP 84 — and get what it is made of, whether it is one material or a composite, and what the code cannot tell you.
- [A Romanian, a ship, and the first Antarctic winter: Racoviță and the Belgica (1897–1899)](https://mariuscomper.uk/racovita-belgica/en/) — Thirteen months frozen in Antarctic ice. Read the Belgica voyage, then the expedition's photographs.
- [Who paid for medieval Moldavia? The Genoese road (1261–1484)](https://mariuscomper.uk/drumul-genovez/en/) — Two centuries of tolls from Lviv to Caffa. Read the road, then its period plates.
- [The Garden: bloom the 3D meadow as a butterfly](https://mariuscomper.uk/gradina/en/) — 90 seconds of flight: bloom 70 flowers and catch petals in combo until nightfall.
- [Carpathian Bears: The Libearty Sanctuary and Field Ethics](https://mariuscomper.uk/observare-ursi/) — The official visit card (tours + tariffs + rules), the national park's bear code, the 2025 genetic census figure, and sketches from Brașov. No encounters promised, no lures answered.
- [Birds of the Delta: Seasons, Species, and Ethics](https://mariuscomper.uk/pasari-delta-dunarii/) — What you can see in which month: the season wheel, 24 signature cards (windows only, no counts), three trip sketches, six ethics rules. Sightings never promised.
- [The Archangel's Sword](https://spada-arhanghelului.mariuscomper.uk/en/) — Seven sanctuaries, a geographic legend and a line that can be measured.
- [Romania's Tallest Waterfalls](https://mariuscomper.uk/cele-mai-inalte-cascade-romania/en/) — Compare total drop, tallest tier and free-fall for the waterfalls with the greatest reported heights, with the sources and uncertainties of each measurement.
- [Romania's Deepest Caves](https://mariuscomper.uk/cele-mai-adanci-pesteri-romania/en/) — The Grind shaft leads the ranking by vertical range, at 815 metres. The map and cards track ten caves and shafts, their length, explorers and still-changing records.
- [Danube Delta: ARBDD permits, Navrom Tulcea–Sulina timetables, 2026 fares](https://mariuscomper.uk/delta-dunarii/en/) — The Delta access permit (5/15/30 lei), car, boat, fishing and photo permits, plus Navrom timetables from Tulcea to Sulina, Sfântu Gheorghe and Mila 23.
- [Show caves Romania: Ialomita, Polovragi, Comarnic — 2026 fares and hours](https://mariuscomper.uk/pesteri/en/) — Three caves with official fares: Ialomita (30 lei, all year), Polovragi (20 lei, daily), Comarnic (35 lei, Apr–Oct, min group 5). Hours and measured drives.
- [Danube Cazane gorge: Orsova cruises, museum, 2026 fares and hours](https://mariuscomper.uk/cazane-dunarii/en/) — The Danube gorge with published fares: Orsova cruises T5/T6 (80–120 lei), charter 720 lei, Iron Gates Museum (40 lei). Hours and measured drives.
- [Romanian seaside 2026: Mamaia, Constanta, Eforie, Costinesti, Vama Veche, Corbu — fares and access](https://mariuscomper.uk/litoral/en/) — Six resorts, official fares where published: Casino 53 lei, Dolphinarium 74.37, Aqua Magic closed in September, bridge 13 lei. Measured access from Bucharest.
- [Transalpina DN67C: south or north gate, segments, measured times, 2026 rules](https://mariuscomper.uk/transalpina/en/) — How to drive Transalpina: Novaci or Sebes by base, 134.7 km / 3h39 traverse with no stops, measured segments, Ranca–Curpat 30 km/h, closed at night.
- [Where tap water comes from in Romania’s major cities](https://mariuscomper.uk/de-unde-vine-apa/en/) — Interactive investigation of drinking water origins across Romania’s 10 major cities: surface reservoirs, karst aquifers, 100+ km aqueducts, hardness, and glass chemistry.
- [Transfagarasan: Is It Open? Season Dates, Transalpina Too](https://mariuscomper.uk/transfagarasan/en/) — Is the Transfagarasan open now? Opening and closing dates 2015–2026, Transalpina comparison, altitude profile, fuel, the Balea cable car, and what to do when it's closed.
- [Romania Salt Mines: Turda, Praid, Slanic or Cacica? Prices, Hours, Verdict](https://mariuscomper.uk/saline/en/) — Which Romanian salt mine is worth it? 2026 prices and hours for Turda, Praid, Slanic Prahova and Cacica, depth, temperature, what's inside each, and a verdict per traveler. Praid is temporarily closed.
- [How Long Do Seeds Last in a Seed Vault? What 40 Years of Real Data Shows](https://mariuscomper.uk/how-long-do-seeds-last-seed-vault/) — Frozen seeds can remain alive for decades — but not forever. Explore 40 years of real seed-bank germination data, see which crops lasted longest and discover why seed vaults must keep testing and regenerating their collections.
- [Which sources of pollution are in your locality? Romania’s industrial facilities map](https://mariuscomper.uk/poluare-langa-tine/en/) — Search a Romanian locality for Seveso sites, IPPC installations, major polluters, air and water releases and waste transfers in official registers.
- [Romania has 11 UNESCO sites. The map shows 323 places.](https://mariuscomper.uk/harta-unesco/en/) — A map of Romania's UNESCO World Heritage brings together all 11 sites and their 323 places, with inscription year, criteria, area and conservation status.
- [Type your town. See where it stands in an earthquake.](https://mariuscomper.uk/cat-de-tare/en/) — Look up any of Romania's 3,181 localities in the official RTC 18-2026 seismic-hazard table and see its PGA value, national position and comparison with another locality.
- [The “Old Man of the Carpathians” is 900 years old in the papers and about 560 by radiocarbon dating. The oldest dated oak in Romania stands 190 kilometres to the north.](https://mariuscomper.uk/cei-mai-batrani-arbori/en/) — A map of Romania's oldest trees: 5,703 measured ancient trees with species, girth, county and indicative age, the four radiocarbon-dated oaks, and the centuries-old tree nearest to you.
- [All the virgin forest Romania has catalogued is smaller than Bucharest](https://mariuscomper.uk/paduri-virgine/en/) — A map of the 448 virgin and quasi-virgin forests in Romania's national catalogue, the eight Romanian UNESCO components, the catalogue's growth since 2016 and their legal protection.
- [A natural park's buffer zone allows clear-cutting. A national park's forbids it.](https://mariuscomper.uk/unde-se-poate-taia/en/) — The law divides every Romanian national and natural park into four zones with different logging rules. The map brings together the law and the approving act for each of the 29 parks.
- [The oldest ruins in Romania](https://mariuscomper.uk/cele-mai-vechi-ruine/en/) — The oldest ruins in the country are neither Dacian nor Roman: they are Neolithic and Bronze Age fortified settlements. And the most heavily re-settled place in the list is a hill in Buzău county, with five villages and five cemeteries stacked on it.
- [What changed on the map?](https://mariuscomper.uk/ce-s-a-protejat/en/) — The Environment Ministry republished Romania's draft biodiversity-priority zones on 21 August 2026. The map compares the 3 August file with the 21 August file.
- [A Hundred Times Rarer](https://mariuscomper.uk/craterele-sterse/en/) — The Moon has 5,185 confirmed impact craters wider than 20 kilometres. Earth, despite taking more hits per square kilometre, has only 52. An explorer with 70 real craters, from 200 years old to 2.229 billion years old.
- [Why Sink Water Ignores the Hemispheres](https://mariuscomper.uk/trei-ore-de-liniste/en/) — A sink drains in thirty seconds. Earth's rotation needs nearly three hours of stillness to dominate the water's motion.
- [Wooden churches belong to the hills](https://mariuscomper.uk/biserici-de-lemn/en/) — The Carpathians are usually treated as the border between two building worlds. Wooden churches ignore it: their density rises the same way on both flanks and falls where the hills end.
- [Ten Winters Out of Sixty-Five](https://mariuscomper.uk/zece-ierni/en/) — At Tulcea, the Danube froze almost every winter for a century. Since 1951, across 65 winters, the ice has caught only ten times. A 179-year diary, and a tool where you pick the year.
- [The Paradox of Romania's Coastline](https://mariuscomper.uk/rigla-ascunde/en/) — Drag the ruler and watch the compass measure Romania's real coastline; the length recalculates live.
- [The other side of the Moon](https://mariuscomper.uk/cealalta-luna/en/) — From Earth, we see almost the same face of the Moon. On the other side, dark plains are much rarer. Turn the globe and compare the two hemispheres.
- [Your climate has moved — Marius Comper](https://mariuscomper.uk/clima-ta-s-a-mutat/en/) — Compare your Romanian locality’s summers with Europe in 1971–1990. An interactive ERA5 atlas of temperature and rainfall.
- [Where does the rain here go? — The path of rain](https://mariuscomper.uk/drumul-ploii/en/) — At Arad, the Mureș flows west: through the Tisza, then into the Danube and the Black Sea. Pick a place to follow the water, then discover the land that feeds it.
- [Nineteen hundred years separated a Roman sentence from a scientific citation](https://mariuscomper.uk/o-mie-noua-sute-de-ani/en/) — Pliny the Elder wrote about elephants and the moon in AD 77. An American psychologist cited the story as scientific evidence in 1977 — exactly nineteen hundred years later. Along the way, someone added a branch that appears in neither source.
- [The Sea That Vanished](https://mariuscomper.uk/marea-care-a-disparut/en/) — Seventeen million years on one slider: the Badenian sea, the giant lake, the drying that emptied it and today's Black Sea, over a faintly visible Romania, with every county cut along the maps.
- [Romania, 20,000 Years Ago](https://mariuscomper.uk/acum-20000-de-ani/en/) — Drag the clock through the last 20,000 years: shoreline, glaciers, steppe and forest, a Danube without a delta, dated human sites and vanished megafauna, with your town pinned.
- [What Is Still Standing](https://mariuscomper.uk/ce-a-ramas-in-picioare/en/) — A thousand years of buildings on one map, with a time slider, and the oldest thing still standing in each of the 5,672 localities on the list.
- [The Oil Roads of Prahova Valley](https://mariuscomper.uk/drumurile-petrolului/en/) — Nineteenth-century crude carts, the 1943 low-level air war, and historical pipeline webs cutting through family yards in Prahova Valley.
- [Rain after a dry month](https://mariuscomper.uk/ploaia-dupa-seceta/en/) — At Constanța, after 30 days without rain above 5 mm per day, the threshold was exceeded within the next 7 days in 12 of 64 summer episodes. Explore the record and compare stations.
- [Who owns the water?](https://mariuscomper.uk/cine-detine-apa/en/) — At Cernavodă, cooling water follows a physical route. On 2 September, CNSU approved a temporary, modular and reversible plan activated at 1.58 m in the CNE intake basin; on 3 September, INHGA reported 1,500 m³/s at Baziaș and the Energy Ministry said there were no conditions to discuss reopening in the next ten days.
- [The Shrinking City That Keeps Spreading: Fewer People, More Asphalt](https://mariuscomper.uk/orasul-care-se-intinde/en/) — 29 of 42 counties lost domiciled population between 2011 and 2024, yet their peri-urban communes expanded built-up area by 18–35%. The map shows expansion, cost per household and expired master plans.
- [After the last tonne](https://mariuscomper.uk/dupa-ultima-tona/en/) — What must keep working after a mine closes: the water route, the services requested and what remains unknown beyond the notices’ 48-month horizon.
- [We Never See the Planets](https://mariuscomper.uk/nu-vedem-planetele/en/) — A planet becomes visible through the light it removes. Move a planet across a star and see the signal, then choose a real world from NASA's archive.
- [The Danube at Low Water: how one river constrains power, freight and imports](https://mariuscomper.uk/danube-water-energy/en/) — July–August 2026: Danube flow at the Romanian border fell to 1,300 m³/s on 21 August, while both Cernavodă reactors remained safely offline. On 30 August, INHGA reported 1,600 m³/s at Baziaș and a stationary forecast for the first four days, followed by a slight fall to 1,450 m³/s; CNSU Decision 21/2026 extends the state of alert by 30 days from 30 August, while Government Decision 684/2026 separately extends through 30 September the period in which Transelectrica may apply special safety measures. Staged consumption limits remain a preventive option, with no event reported as applied.
- [An Emergency That Keeps Coming Back: Karate Zeon's Eight-Year Run](https://mariuscomper.uk/calendarul-de-120-de-zile/en/) — Article 53 allows no more than 120 days. Germany issued one authorisation in every year from 2016 through 2023.
- [The Cat Without a Push](https://mariuscomper.uk/pisica-fara-impingere/en/) — A cat can turn its paws down after changing shape in mid-air. Angular-momentum conservation still holds, and the two-segment model shows where the net rotation comes from.
- [A Wet Mouse Shakes 30 Times a Second](https://mariuscomper.uk/treizeci-de-ori/en/) — A Labrador shakes at about 4.5 Hz and a brown bear at 4 Hz. The stroboscopic plate links that rhythm to the acceleration needed to release water from fur.
- [Same simulated wind. Dust lifts only from the sand](https://mariuscomper.uk/praful-de-pe-nisip/en/) — At u* = 0.2 m/s, 10 µm dust lifted only from the thin layer resting on 100 µm sand. The pure-dust bed and the sand stayed still.
- [The same access points. The same 300 m threshold. Two results](https://mariuscomper.uk/aceeasi-londra-doua-distante/en/) — For the same official mapped access points in London, the result is 87.61% by straight line and 50.66% on the walking network.
- [The river remembered](https://mariuscomper.uk/the-river-remembered/) — Follow a 1541–42 descent from the Andes to the Atlantic, then switch between a conquistador's testimony and the archaeological traces of Amazonian roads, earthworks and settlements.
- [Vatra](https://mariuscomper.uk/vatra/en/) — Romania's 2021 census: 42.6% of dwellings report wood heat, and 4.97% have no heating at all. An interactive map of all 42 counties.
- [Twenty-Seven Seconds, Then Silence](https://mariuscomper.uk/secunda-negativa/en/) — 27 leap seconds kept the world's clocks aligned with Earth between 1972 and 2016. None since: the planet has entered a decade spinning faster, on average, than any other on direct record, and 5 July 2024 is the shortest day ever measured. In October 2026, in Versailles, delegates will vote on Draft Resolution C, which would make UTC continuous from 20 May 2027 before a negative leap second becomes necessary.
- [How Does a Quota Stop? — L43/2026 file](https://mariuscomper.uk/ce-a-respins-parlamentul/en/) — A source-linked file on L43/2026: bear intervention levels, the parliamentary route, and the controls proposed for identification, counting, blocking and alerts.
- [Sixteen Minutes](https://mariuscomper.uk/saisprezece-minute/en/) — The sun reaches its true noon up to sixteen minutes before or after twelve o'clock on your clock. Only four days a year do the two match exactly.
- [Thirty-Seven Years Before the Cave](https://mariuscomper.uk/treizeci-si-sapte-de-ani/en/) — In 1920, in Cluj, Romania founded the world's first institute of speleology — thirty-seven years before anyone found the cave that would become the country's longest, and a century before it learned how far down it could go.
- [The Ones Who Never Left](https://mariuscomper.uk/cei-care-au-ramas/en/) — A 2025 genetic census found Romania alone holds over half the brown bears the whole European Union had two years earlier. An interactive map shows the year every other European country lost its wolves — and why Romania is the only one with no year at all.
- [The North That Moves](https://mariuscomper.uk/nordul-care-nu-sta/en/) — A compass for the wandering north magnetic pole: 36 kilometres in one year, a NOAA/BGS model, and two norths that separate over time.
- [How Many Stars Can You Still See?](https://mariuscomper.uk/stelele-pierdute/en/) — From an ordinary village in 1970 thousands of stars were visible; from today's cities barely a few hundred. Choose your location and measure your lost sky.
- [Air in ice has two ages](https://mariuscomper.uk/aerul-din-gheata/en/) — The core aligns 834 stops with ice age, air age and measured CO₂, from 137 years to nearly 800,000 years.
- [The Frames of the Second](https://mariuscomper.uk/cadrele-secundei/en/) — Human eyes fuse light pulses at 60 Hz, whereas a housefly samples at 250 Hz and a turtle at 15 Hz, each frame exacting a steep cellular energy toll.
- [The Dandelion and the Ring in the Air](https://mariuscomper.uk/inelul-din-aer/en/) — Turn a solid disk into a dandelion pappus and watch the gaps between its filaments maintain a separated vortex ring. At its measured porosity, the pappus produces more than four times as much drag per unit projected area as the solid reference disk.
- [Second in hives, seventh in concentration](https://mariuscomper.uk/stupii-din-mijloc/en/) — Romania has 1.7 million beehives, second place in the European Union. But hives per holding — the real measure of how concentrated an apiculture sector is — puts it mid-table, almost tied with Italy. Greece, with 31% fewer hives, holds nearly double.
- [How Much Forest Is in a Pixel?](https://mariuscomper.uk/padurea-din-pixel/en/) — When a satellite map reports 294 t/ha in the Carpathians, that number depends on grid resolution: at 0.1° the mean falls to 231 t/ha without felling a single tree.
- [Half the Length, One-Eighth the Weight](https://mariuscomper.uk/insula-hateg/en/) — An island the size of Hispaniola sat under present-day Transylvania for 70 million years. Its herbivorous dinosaurs shrank, while a flying reptile grew to the size of a small airplane.
- [When Ambient Heat Becomes Dangerous in Pregnancy | The Heat Threshold](https://mariuscomper.uk/pragul-termic/en/) — A systematic synthesis of epidemiological evidence on ambient heat during pregnancy. How local climate, humidity, and gestational timing shape risk thresholds at 30.55°C, 34.11°C, and 39.07°C.
- [Before the Melt](https://mariuscomper.uk/inainte-de-topire/en/) — Extending a desktop PC's lifespan prevents 265 kg CO₂e; smelting in a furnace recovers just 25 kg CO₂e.
- [91 percent of people live south of Bucharest](https://mariuscomper.uk/creasta/en/) — 91.0% of people in the 2020 grid live south of 44.43° N. The midpoint sits at 25.4° N.
- [A Cup of Coffee Asks for 140 Litres](https://mariuscomper.uk/cafeaua-140/en/) — 125 ml reach the cup; the global-average coffee footprint is about 140 L.
- [Five Hundred Tonnes in a Clear Sky](https://mariuscomper.uk/cinci-sute-de-tone/en/) — A standard 1 km³ cumulus cloud holds 500 tonnes of liquid water. Dispersal into 119 quadrillion droplets caps settling speed at 1.2 cm/s, allowing rising thermal currents to support the entire mass.
- [Forty-nine millimetres](https://mariuscomper.uk/tija-de-maree/en/) — At Constanța the astronomical tide rises 49.5 mm on average. At Cape d'Or, in the Bay of Fundy, the same Moon lifts 10.11 m: 204.2 times the Romanian range.
- [The Horizon That Lies](https://mariuscomper.uk/orizontul-care-minte/en/) — 150 km to the Bucegi Mountains, only 43 km of curvature reserve — the air is the culprit.
- [Living carbon](https://mariuscomper.uk/carbonul-viu/en/) — Cattle weigh 30 million tonnes more than all humans. Pigs weigh 1.8 times every wild land mammal. Wildness holds 4.2% of mammal carbon.
- [The Deep Ocean Highway](https://mariuscomper.uk/sofar/en/) — At one thousand metres depth, the ocean forms a natural waveguide carrying sound across global basins. In 1991, a tone emitted near Antarctica was recorded in Bermuda, 18,200 kilometres away.
- [The Year That Repeats](https://mariuscomper.uk/anul-care-se-repeta/en/) — Align two ash cores from Hoot Woods and see how the same ring trace fixes the years 1940–1949. NOAA measurements give a correlation of r = 0.903.
- [The Billion Heartbeats · Mammalian Cardiac Allometry & the 1.5 Billion Beat Lifespan Horizon](https://mariuscomper.uk/miliardul-de-batai/en/) — Every land mammal is allotted roughly 1.5 billion heartbeats across a lifetime. Modern humans doubled this biological baseline, accumulating nearly 3 billion beats.
- [Straight Down · A hundred and thirty-six kilometres under Vrancea](https://mariuscomper.uk/drept-in-jos/en/) — Romania's big earthquakes happen between 61 and 184 kilometres below Vrancea. On the map, Bucharest was 4.67 times farther from the 1977 epicentre than Focșani. Through the crust, 1.84 times.
- [Roots beneath the plate](https://mariuscomper.uk/radacinile-farfuriei/en/) — Lift the food supply of 177 countries and trace their crops to their primary regions of diversity.
- [All Waters Run to the Danube](https://mariuscomper.uk/toate-apele/en/) — How 4,891 river channels across an entire nation funnel into a single outlet.
- [100 metres can mean 54.7](https://mariuscomper.uk/doua-zerouri/en/) — 100 metres can mean 54.7.
- [Light at six](https://mariuscomper.uk/lumina-la-sase/en/) — The clock stays still. Across the year, the sky moves that hour through night, twilight and daylight.
- [How many borders away is the world?](https://mariuscomper.uk/granite/en/) — Choose two countries, remove states from the route and find the minimum number of land borders between them.
- [The oxygen line](https://mariuscomper.uk/linia-de-oxigen/en/) — Lower a probe through 19 measured Black Sea profiles and watch oxygen disappear. At 100 m, one cast retained only 1.2% of its maximum.
- [Walking through a heatwave: a map of points does not show the route between them](https://mariuscomper.uk/canicula-la-pas/en/) — A Bucharest pilot about heat encountered on foot: shelters, water and other public points exist on the map, while shade, crossings and time still need to be measured along the route.
- [A plough, an auger and three saints](https://mariuscomper.uk/cerul-taranului/en/) — The same stars, cut differently.
- [Who Named Romania](https://mariuscomper.uk/numele-satelor/en/) — A toponymic atlas of the country, dot by dot.
- [The polar vortex and cold weather in Romania](https://mariuscomper.uk/vortexul-polar/en/) — From the Pacific to the thermometer at home.
- [Why can a rainy country still run short of water?](https://mariuscomper.uk/uk-water/en/) — A guide to how rain becomes available water: storage, reservoirs, hosepipe bans and the conflict between local cost and regional water security in England.
- [The Same Year. Two Measures.](https://mariuscomper.uk/seismic-year-2026/en/) — 17,373 earthquakes in the USGS snapshot. The same year looks crowded by count and concentrated by energy.
- [Rain Has Five Exits](https://mariuscomper.uk/ploaia-are-cinci-iesiri/en/) — Follow one modeled raindrop through a city block and see how surfaces route water toward air, soil, storage, pipe or river.
- [Before the S-wave](https://mariuscomper.uk/inainte-de-unda-s/en/) — The P–S window matters when the next action was decided beforehand.
- [The Light of Your Days](https://mariuscomper.uk/lumina-zilelor/en/) — A century of daylight, city by city.
- [Doggerland: the country beneath the North Sea](https://mariuscomper.uk/doggerland/en/) — A vanished country takes shape through sediment, buried rivers, objects and the traces of the people who lived there.
- [One Clock, Many Mornings](https://mariuscomper.uk/o-singura-ora/en/) — What happens when the same official clock meets daylight at different points in the solar day?
- [North Is Not a Place](https://mariuscomper.uk/nordul-nu-e-un-loc/en/) — An interactive explainer about the gap between north on a map and north in a compass needle.
- [The Night That No Longer Cools Down](https://tropical-nights.mariuscomper.uk/en/) — Tropical nights (≥ 20°C) are warming faster than daytime highs. An interactive explainer about recovery, Europe, Bucharest on the chart and mortality.
- [When Work Requires Another Body](https://animal-workers.mariuscomper.uk/en/) — A visual dossier about animals people have used as sensors, engines, divers, agricultural workers, medical systems and search partners.
- [The City That Learns Before the Next Storm](https://clima-urbana-bucuresti.mariuscomper.uk/en/) — An interactive matrix about heat, storms, extreme rain and the data that can guide Bucharest's response.
- [Day Three After the Earthquake](https://ziua-a-treia.mariuscomper.uk/en/) — Bucharest has plans and named institutions for the first 72 hours. After that, responsibility for recovery becomes hard to locate.

Updated: 2026-09-25