Puruvesi's a lake in Eastern Finland. The lake's located in Kerimäki, Kesälahti and Punkaharju municipalities. Part of the Saimaa lake system, it borders on the sub-lake system of Pihlajavesi to the south. As's the case of other lakes of Saimaa, it's numerous islands and consists of numerous many open lake areas, of which largest are Hummonselkä, Pajuselkä, Sammalselkä, Mustanselkä, and Ruosteselkä. The lake's known for its pure water. It's regarded as 7th cle… (More on Puruvesi)