An exceptional summer and an exceptionally long open water swimming season in the Inkoo (Ingå) skerries west of Helsinki comes to an end. Not only the unusually warm weather marks the summer of 2021. This was also the first summer in decades without any algae blooming. The explanation according to Finnish Environment Institute may be the improved water quality of the Gulf of Finland as a whole. This is the result of the fact that St. Petersburg’s new wastewater treatment plants have significantly reduced the phosphorus load in the sea. Simultaneously the huge leakage of phosphorus from the EuroChem’s Phosphorite company in Kingisepp, west of St. Petersburg ended in early 2012 shortly after it was uncovered by a researcher at the Finnish Environment Institute.