Gatun Lake (Sp. Lago Gatún) is an artificial lake situated in the Republic of Panama, and part of the water system for the Panama Canal.

The lake was created between 1904 and 1914 by building the Gatun Dam across the Chagres River . At the time it was created, Gatun Lake was the largest man made lake in the world, and the dam was the largest earth dam.

Gatun Lake is 26 metres above sea level. With its watersheds it serves as a reservoir for the three canal locks since there is a dry season from late December to early April in Panama. With the creation of the lake many hilltops became islands. The biggest and most known of them is Barro Colorado Island.