Algal bloom in the Baltic Sea

Central Baltic Sea

Dates of acquisition:
• 2026.06.22 | 09:39:14 UTC
• 2026.06.23 | 10:00:31 UTC

Sensors: Sentinel-3B OLCI, Sentinel-2C L1C

Coordinates: ca. 57°N, 20°E

As is typical in June, when daylight hours are at their peak, an algal bloom occurs in the Baltic Sea. This year, the bloom was further intensified by high temperatures.
A Sentinel-3 image from 22 June (Figure 1) shows that the bloom extends across the entire central part of the Baltic Sea. A Sentinel-2 image from 23 June (Figure 2) provides a more detailed view of the situation in the area between the island of Gotland to the west and the Estonian island of Saaremaa and the Latvian coast in the east. The image has been contrast-enhanced to make the structure of the water more visible.