What’s wrong with water in the Gdansk Bay?

In Gdansk, Gdynia, General, Sopot, Tourism

The warm weather is encouraging to have a bath in the sea. Since Monday however, all beaches in the Gdansk Bay have red flags. This means we cannot swim in the Bay. Additionally, the water has a nasty color which scares many passers-by. What is it? What is the danger for us?

No bathing in Gdansk Bay

Since Monday, the 23rd of July, the tourists see red flags at all beaches in Tricity and in Gdansk Bay area. The Sanitary Inspectorate forbade entering the water due to a high amount of Cyanobacteria. This colonial bacteria is now in bloom in the Gdansk Bay what results in the blue-green color of the water.

The reason for blooming is high temperature and lack of proper mixing of waters in the Gdansk Bay. Additionally, water in the Bay is rich in phosphate. Those originate from fertilizers flowing from fields into rivers and as a result entering the Baltic Sea.


The studies on the influence of Cyanobacteria on human health are still developing. The scientists have confirmed that the bacteria produces specific toxins which are or may be harmful to people and animals. Though there were several cases of human poisoning, it is still hard to properly assess the risk.

Due to some recent studies, high exposure to significant amounts of toxins originating from Cyanobacteria can lead to the development of ALS.

How to protect ourselves

The first thing to do is not entering the water in the Gdansk Bay. If you really want to enjoy a swim, try to locate safe areas. The Sanitary Inspectorate has published a website with an online map of bathing spots. Though the website is in Polish, it is easy to recognize that red pinpoints mean swimming ban and green suggest clean water.

The next examination of water will take place on Monday, the 30th of July. We will keep on informing on the further decisions of The Sanitary Inspectorate.

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