Lake Peipus Lake Peipus Lake Peipus (; ; ) is the largest transboundary lake in Europe, lies on the border between Estonia and Russia. The lake is the fifth-largest in Europe after Lake Ladoga and Lake Onega (in Russia north of St. Petersburg), Lake Vänern (in Sweden), and Lake Saimaa (in Finland). Lake Peipus represents a remnant of a body of water which existed in this area during an Ice Age. It covers , and has an average depth of , the deepest point being . The lake has several islands and consists of 3 parts: The lake is used for fishing
Siskiwit Lake (Isle Royale) Island) in Lake Mindemoya (which is larger than Siskiwit Lake, but not the largest lake on Manitoulin Island, which is Lake Manitou) on Manitoulin Island (which is larger than Isle Royale) in Lake Huron is believed to be the world's largest island in a lake on an island in a lake. Treasure Island may also contain ponds (as do several lake islands in Manitoulin Island) which may contain rocky islands larger than Moose Boulder. But Lake Huron is not the largest lake in the world.) (The largest island in a lake on an island in a lake on an island