Saint Ana Lake in the Ciomatului Mare crater is the only lake of volcanic origin in Central and Eastern Europe and the most visited tourist attraction in Szeklerland.
It is surrounded by the steep walls of the volcanic cone of Monte Ciomat, with several higher peaks: Ciomatul Mare (1301 m), Ciomatul Mic (1238 m), Tata Hill (1174 m) or Piscul Pietros (1125 m).
The lake, unique in Europe, is located at an altitude of 946 m, has a diameter of 1737 m and a greatest depth of 7 m.
From the crater rim, 13 temporary streams formed after the rains carry water and gravel into the lake. The lake is fed by rainwater and water from snowmelt.
The lake's sedimentation process began at the northern and western edges, with the lake floor being covered by an increasingly thick layer of mud. The lake is currently 6.5 m deep at its deepest point.
In good weather, especially without wind, you can see gas bubbles rising from the bottom of the lake, which are actually an expression of post-volcanic activity. In the northern, northeastern part of the lake, you can see a layer of floating peat about a meter thick.