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
Wollaston Lake out of the northeastern side of the lake and into Reindeer Lake, which drains via the Churchill River system into Hudson Bay. Wollaston Lake's main inflow is the Geikie River which flows from the southwest into the southwest section of the lake. If the aforementioned oceanic definitions are used, then the Geikie is the largest river in the world to flow naturally into two oceans. Wollaston Lake is also the largest lake entirely within Saskatchewan, although the Saskatchewanian portions of Lake Athabasca and Reindeer Lake are both larger. Samuel Hearne learned of the lake in 1770 and David Thompson noted