Authorities in northern Germany are urging swimmers to avoid areas affected by toxic blue-green algae blooms, which have spread across coastal and inland waters, posing health risks.

Health officials in northern Germany have issued warnings to swimmers about the presence of harmful blue-green algae, also known as cyanobacteria, in several coastal and inland water bodies. The algae blooms, which can produce toxins causing allergic reactions and other health issues, have been detected in areas along the Baltic Sea and various lakes in Mecklenburg-Western Pomerania and Schleswig-Holstein.

Affected locations include popular coastal spots such as Rostock-Warnemünde, Kühlungsborn, Heiligendamm, and Wohlenberger Wiek near Wismar, as well as rivers and lakes like Peenestrom, Schwandter See, and Melzer See. While swimming bans have not been imposed on these waters, authorities are advising caution and recommending avoiding areas where visible algae blooms are present. Satellite imagery has revealed extensive algae mats stretching from Mecklenburg-Western Pomerania to Denmark’s coastline.

In Schleswig-Holstein, swimming bans have been enforced at several lakes, including Bordesholmer See, Brahmsee, Warder See, and Dörpsee, all located in the Rendsburg-Eckernförde district. These restrictions are expected to remain in place until midweek. Officials have advised swimmers to avoid entering water where visibility is compromised due to bluish-green discoloration, and parents are urged to keep children away from affected shorelines and shallow waters. The spread of algae blooms is influenced by weather conditions and can change rapidly.