Suez 2021: did reopening the canal also clear the queue?

Ever Given ran aground in the Suez Canal on 23 March 2021. With passage between the Mediterranean and Red Sea blocked, ships began to wait. ESA’s Sentinel-1 comparison, published on 26 March, shows routine traffic on 21 March and the blockage on 25 March.

To follow the queue in the gulf, we used NASA Earth Observatory’s file published on 31 March. Its images cover dates before the incident through the day the canal reopened. They are observations taken at separate moments, with gaps between them.

The first two images were acquired on 11 and 27 March. The coastline and the narrowing northern end of the gulf help locate the same place. With identical crops, more small, elongated traces are visible at sea on 27 March. NASA identifies them as waiting ships.

The highlighted area in the video directs attention to those traces. We did not use it to count ships: clouds cover parts of the scene, and the small marks cannot always be distinguished reliably.

The night images come from VIIRS, an instrument aboard the Suomi NPP satellite that records light at night. In the 1 February, 27 March and 29 March views, first find the city lights on land, then look at the points inside the gulf. This makes the concentration of lights at sea easier to see.

The daytime and night images have different resolutions, so we did not match them pixel by pixel. Both appear in the same NASA file. ESA’s separate radar observation shows the blockage through another satellite record.

The Suez Canal Authority’s notice of 29 March announces successful refloating in its headline. The body makes clear that work remained: the vessel’s direction had been restored by 80 percent, manoeuvres would continue, and navigation would resume after full alignment.

NASA’s account, published on 31 March, says the canal reopened on 29 March and that clearing the waiting traffic took time. Lights are also visible inside the gulf in the night image dated 29 March. The image does not establish the acquisition time relative to reopening, so we do not use it as an hourly traffic record.

We downloaded NASA’s source images and checked their acquisition dates. The zooms and moving divider in the video make it easier to follow the same area across different days. NASA processed the satellite data and supplied the initial interpretation of the shipping traffic.

The images and the announcement contribute different parts of the account. Freeing the ship allowed passage to resume; the waiting vessels still needed time to move through. Source links, original files and crop settings were recorded so the comparison can be checked again.