Iceland's Lake Kleifarvatn is the largest lake on Reykjanes, the southernmost of the three large peninsulas which extend off the western coast of this North Atlantic island nation. The lake is unusual in that all water exchange occurs underground and out of site; there are no visible sources or outlets of the lake. The lake covers about 8 square km (around 3 square mi.) and is quite deep - almost 100 meters or about 320 ft. Check out the lake from a drone perspective in this video by contributor Breath of Iceland.