The Black Sea, off the Danube Delta · every clear day, 2019–2026
The queue off Sulina: ships waiting to enter the Danube, counted from space
On a typical day before the war, the Sentinel-2 satellite showed 1 ship off Sulina, the Romanian port at the mouth of the Danube’s shipping channel. On 5 September 2026: 71 ships. Most of them lie in Romania’s territorial sea. In October 2026, commercial ships were attacked in these waters.
5 September 2026
71 ships
On a typical pre-war day: 1 ship
ship in Romania’s territorial seaship beyond it12-nautical-mile limit
The image shows the sea east and south of the mouth of the Sulina channel, a window of about 31 by 29 kilometres, on 3 November 2021: 1 ship. On the 57 clear days before 24 February 2022, the typical count was 1 ship.
Each ring is a ship found by the same rule on every image: an object of 2 to 200 pixels of 20 metres, bright in two infrared bands, on open water.
After Russia blocked Ukraine’s seaports in 2022, Ukraine’s grain took the Danube route, through the river ports of Izmail and Reni. Sea-going ships enter the river through the Sulina channel and wait at anchor off its mouth.
On the 26 clear days between May 2022 and October 2023, the typical count was around 68. The image is from 21 July 2023: 68 ships. On 11 August 2022, the Tulcea harbour master counted 96 ships waiting in Romanian territorial waters to enter the Sulina channel, plus 14 more for Ukraine’s Bystroe channel.
From 2024 to July 2026, on 63 clear days, the typical count fell to 17. That is fewer than in 2022–23, but against a single ship before the war, the queue never went away. The image is from 14 August 2025: 17 ships.
On 5 September 2026, the image shows 71 ships. In the same weeks, shipping firms quoted by Reuters and the trade press put the queue at 70–80 vessels, with two-week waits to enter the channel, because of a shortage of pilots, air-raid alerts that halt Ukraine’s river ports, and weather.
The dashed line is the limit of Romania’s territorial sea, 12 nautical miles from the Sulina–Sacalin baseline set by Law 17/1990. Of the 3,219 ship sightings since May 2022 (the same ship can appear on several days), 81% lay in Romania’s territorial sea, 7% in Ukraine’s, north of the maritime border, and 12% beyond both.
What the image shows is position. Flag, cargo and destination are not visible in the pixels; that the ships are waiting for the Sulina channel is inferred from where and when they are.
October 2026: ships attacked in the waters where they wait#
On the evening of 14 October, the ship Yara J caught fire at anchor in Romania’s territorial waters, south-east of Sulina; everyone on board was safe, and the cause was not officially confirmed. The next morning the ship Wine Trader caught fire about 13 nautical miles south-east of Sulina: of the 12 people on board, 5 were rescued and 7 were reported missing. Romania’s Ministry of National Defence said on 17 October that “several commercial ships were hit by drones in the Black Sea, including in Romania’s territorial waters”.
The queue did not break up: on 19 October, shipping press again counted about 82 vessels in the Sulina roadstead. The last clear image before 30 October is from 3 October 2026, before the strikes: 33 ships. Up to 30 October, no satellite pass after that day gave a clear image of the window: after 15 October, cloud covered 73% to 100% of the image tiles.
The counts below come from the harbour master, the river administration and shipping firms, not from images, and they are not from the same days as the images. Where a clear day falls within four days, both show dozens of ships, but they do not match exactly: the queue changes from day to day, and the satellite window does not cover the whole roadstead.
Reported on
Reported
By
Nearest clear day
Satellite
11 August 2022
96
Tulcea harbour master: ships waiting to enter the Sulina channel
no clear day within ±4 days
9 August 2023
≈60
Lower Danube River Administration: “almost 60”
5 August 2023
93
26 August 2026
≈70
Avalon Shipping, quoted by Reuters: “about 70” in the Sulina roadstead
24 August 2026
63
7 September 2026
≈80
Avalon Shipping, quoted by USM: “about 80”
5 September 2026
71
19 October 2026
≈82
USM: “about 82” in the roadstead
no clear day within ±4 days
How the ships were counted, and what cannot be seen#
The images come from the Sentinel-2 satellites of the EU’s Copernicus programme, which pass over Sulina every few days. From January 2019 to 30 October 2026, 768 days with images under 60% cloud were read. Where two satellites passed on the same day, the cleaner image was kept. A day counts only if the image covers the whole window and is almost free of cloud and shadow: 184 days.
The counting rule was fixed before it was applied to the whole series: a ship is an object of 2 to 200 pixels of 20 metres, much brighter than the sea in the same image in near-infrared and in short-wave infrared. The channel-mouth area, a box of about 6 by 5 kilometres with the jetties and the beach, which shine the same way, is not counted, and neither are ships waiting inside it. Fixed objects, appearing in the same place on more than a fifth of the days, were looked for: none were found.
Two tests were added after a first pass through the data showed that small clouds slip past the official classification: a day with three or more large patches bright in blue counts as cloudy, and a day where more than 0.1% of the sea passes the ship test, the area of more than 300 ships, counts as sun glint on the waves. Neither looks at the ship count. Of the 184 days, 31 were removed this way, leaving 153. No day was removed by eye.
Small clouds can still leave a few false rings on some days, which is why the text uses the typical count for each period. At this resolution a ship is a few pixels: small boats do not show, two ships side by side can count as one, ships outside the window are not counted, and the image cannot tell a ship at anchor from one under way. Cloudy days are gaps in the series.