Lake Saint Anne

Lake Sfânta Ana is the only crater lake in Romania located in the volcanic crater of the volcano named Ciomatu Mare 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.

It has an oval form and an area of 220,000 m².

Source: Wikipedia