Since measurements began in 1969, the North Sea has never been as warm as it was last year: an average of 11.6 degrees Celsius was recorded in 2025 according to research by Germany’s Federal Maritime and Hydrographic Agency, the BSH, which warns of the consequences of increasingly warmer seawater in the North Sea. ‘We are seeing more unstable weather and weather systems that become blocked, leading to droughts, long heat waves and water bombs,’ explains Jan Seys of the Flanders Marine Institute, the VLIZ.