Along with those islands, one of the lake's most famous features are the floating islands. They didn't exist in the former peat bog and began appearing after 1948, when the lake was created. They are formed when at high water level, loose chunks of peat thick break off the shore. It is estimated that the peat chunks took 5,000 years to form. There are up to 30 floating islands at the time. Driven by the wind, they float from one shore of the lake to another, carrying the flora and fauna, and serving as shelter and a food source for fish. For that reason, they are an attractive target for fishermen, however it is forbidden to visit them or disturb them because of the unique animal and plant ecosystems, though walking on them is practically impossible since they don't have solid ground.