Secret Lake is a meltwater lake 2 nautical miles (3.7 km) west of Ares Cliff, near the east coast of Alexander Island, Antarctica. The lake is situated in a north-west facing glacial cirque and is fed from an area of stagnant ice. It lies 100 m above the east edge of Mars Glacier and is visible only from the cirque or from the air. The lake was first mapped by Directorate of Overseas Surveys from satellite imagery supplied by U.S. National Aeronautics and Space Administration in cooperation with U.S. Geological Survey. The name by United Kingdom Antarctic Place-Names Committee refers to the secluded and isolated location of the lake.