Kyyvesi (transl.Viper Water) is a rather large lake in the Southern Savonia region of Finland. Spite its size (129,95 km²) it's very shallow and extremely rocky. Motorboating is recommended only for very experienced boaters as many of the rocks have not been mapped. Also, the limited amount of landing sites is a hindrance in moving swiftly through the lake. A general bathymetric chart was completed in 2006. Canoes, kayaks and rowing boats are recommended for visitors. There is a two-lake canoein route Kyyvesi–Puula with nice little harbours. The water is dark for the catchment area is mostly swampy terrain.