Guide
The caldera holds five lakes at 2,247 metres, two of them large, and the provincial directorate describes the biggest as the largest crater lake in Türkiye and the second largest in the world. The crater left by the eruptions measures 48 square kilometres at its mouth and 36 at its floor; the Büyük Göl averages 100 metres deep and reaches 155 at its deepest point.
Its water is cold and fresh, fed by snow and springs; analysis showed it clear, colourless, odourless and of normal drinking quality, with radioactivity within normal limits and a pH of 7.4. The hot springs around the lake are the last traces of the volcanic activity. A handful of mirror carp put into the lake in 1986 bred fast enough that it can now be fished. The area was protected in 2003 and declared a Ramsar wetland of international importance in 2013. Three districts of Bitlis share it — Tatvan, Ahlat, Güroymak — and it is 32 kilometres from Bitlis, 62 from Muş. The source is inconsistent on three points: it calls the site a natural monument in its heading while the record here is a national park, gives the declaration date as both 26 and 31 October 2003, and its area as both 4,874.96 and 4,804.7 hectares.
- Designated
- 19.08.2026
