Adjacent to the volcano is a caldera, which is filled partially by the crater lake known as Segara Anak or Anak Laut (Child of the Sea), due to the color of its water, as blue as the sea (laut). This lake is approximately above sea level and estimated to be about deep; the caldera also contains hot springs. Sasak tribe and Hindu people assume the lake and the mount are sacred and some religious activities are occasionally done in the two areas. UNESCO has made Mount Rinjani Caldera a part of the Global Geoparks Network in April 2018.