Blooms of cyanobacteria occur practically every summer in the Baltic Sea, covering large areas of the sea during July-August, and having a substantial influence on ecosystem and marine services. That is why Finnish Environment Institute SYKE has published an extensive, weekly overview of cyanobacterial occurrence in Finnish inland waters and sea areas already since 1998. The overview is based on monitoring of the state of the environment in collaboration between SYKE and several local authorities. The activity of some organizations has also significantly increased the number of observation points for cyanobacterial blooms, especially on the SW and S coasts of Finland. Today, the national cyanobacterial bloom monitoring network includes > 400 permanent observation sites around…