Diomedes Lake (Bulgarian: езеро Диомед, romanized: ezero Diomed, IPA: [ˈɛzɛro dioˈmɛt]) is the trapezoidal lake 480 m long in southeast-northwest direction and 112 m wide near the west extremity of Robbery Beaches on Byers Peninsula, Livingston Island in the South Shetland Islands, Antarctica.

It has a surface area of 4.55 ha, and is separated from the waters of Barclay Bay by a 16 to 40 m wide strip of land, and surmounted by Penca Hill on the south and Enrique Hill on the northwest.

The lake and its vicinity lie in a restricted zone of scientific importance to Antarctic microbiology, part of the Antarctic Specially Protected Area Byers Peninsula.

[2] The feature is named after the mythical king Diomedes of Thrace.

This article includes information from the Antarctic Place-names Commission of Bulgaria which is used with permission.