The caldera is located west of Lake Van in the Tatvan, Ahlat and Güroymak districts of Bitlis Province. It is named after the biblical figure King Nimrod. The caldera is far from Tatvan, and from Ahlat. With its width of nearly, the crater of Nemrut Volcano is one of the largest calderas of the world. The western half of the crater is covered by the lake. At the summit, there are five lakes, two of them existing permanently and the others seasonal. The biggest of the lakes is Lake Nemrut in the form of crescent. It contains freshwater of colorless, odorless and drink water quality. Lake Nemrut is situated at an elevation of about above main sea level. It has an area of, and its average depth is about with a maximum depth of. Nemrut Caldera is on the youngest volcanic cone in Turkey, which is in a not-eroded state. This unique structural geomorphology make it a subject of scientific research.
Biota
Flora
About 450 plant species were recorded in and around Nemrut Caldera, around 200 of them belonging to the region. The diversity of the flora points out to the variation of climate conditions in the past. Around 38 of the existing plant species are endemic. The upside down tulip, which grows here, is a world-famous flower. The climax vegetation of Nemrut Caldera forms the haired birch and the trembling aspen. Other notable plants growing around two lakes of the caldera are the trees dwarf juniper, Norway maple, European mountain ash, common buckthorn , sessile oak, pedunculate oak, white willow, and the shrubs coinwort cotoneaster, cherry plum, grey willow, Greek juniper, breaking buckthorn, alder buckthorn and mahaleb cherry. Steppe-like vegetation is spread over wide areas in the caldera. Those are mainly species of milkvetch. Other subshrubs and herbaceous plants are prickly thrift, sainfoin, sheep's sorrel, Thymus, Alyssum, sheep's fescue, Salvia, Ranunculus, Silene, rabbitfoot clover, Pimpinella, Artemisia, squarrose . Reedy areas are present In the northwestern part of Lake Nemrıt.
The caldera was registered a natural monument in 2003. The protected area around the crater lake covers. Nemrut Caldera Natural Monument is protected in the status of a tourist attraction, a protected area of first degree and a wetland. The government of Turkey designated the wetland of the caldera as the 14th Ramsar site of the country on April 17, 2013. It is not permitted to cut reed in the caldera and to fish in the lake, although some livestock grazing takes place around the caldera. A winter sports and ski center was established on the southern slope of the caldera in 2007. The main threat in terms of ecology is overgrazing.
