Lake Saint Anne (in Hungarian Szent-Anna to) is a volcanic lake, the only such lake throughout Romania. Harghita county is located within the massive Ciomatu, from left Olt near Tusnad. The lake is located on the bottom of the crater of an extinct volcano called Ciomatu (or, according to other sources, Ciomadu) Puciosu volcanic massif, where the most recent volcanic eruption in the Carpathians and Eastern Europe, which took place a few tens of thousands years (probably more recently 42,000 years ago).
Lake supplement their water from rainfall only, with no springs. Water purity is close to that of distilled water, with only 0.0029 ml mineral. Trophic capacity due to low lake water and lake bottom and emanations pits by the crater walls.
Mohos swamp at 1056 meters altitude, situated near Lake St. Ann, is a nature reserve and is the place of residence of many unique species of plants.
Tanovic Mohos sits in one of the mountain crater remains Csomad a height of 1050 m, in Harghita County. It has a diameter of 800 meters and an area of ??80 ha. Peat thickness is 10 m, has a quantity of 3 million cubic meters (cubic). Mohos the old lake disappeared, nemairamanand than a swamp and abundant vegetation comprised tail Matthew-of-mind. Disappearance Lake and Lake regressive erosion due Veres, pouring it in Olt and umplarii the ground.
(Translated with Google Translate)