Lake Sfânta Ana (Romanian pronunciation: [ˈsfɨnta ˈana]; Hungarian: Szent Anna-tó; lit.

'Saint Anne Lake') is the only crater lake in Romania[1] located in the volcanic crater of the Ciomad volcano of the Eastern Carpathians, near Tușnad in the Natural Reserve of Mohoș, Harghita County, Romania.

Palynology studies concluded that the history of Lake Saint Anne began about 9,800-8,800 years ago, at the stage of peat bog and shallow lake.

The depth of Saint Anne Lake is constantly decreasing.

Near the lake there is a Roman Catholic chapel dedicated to Saint Anne.