Lake Nar is a crater lake around 21 meters deep and covers 0.7 square kilometers in area, which means that it is a tiny one. The geothermal activity around the lake gave rise to hot springs. It is declared as a natural site to protect rare species of algae. The water of Nar Lake changes dramatically with the seasons. The lake's water is extremely chilly in the winter however temperature rises in spring and while the bottom is cold and without oxygen the upper parts are warm. Early in the summer, planktonic algae precipitate calcium carbonate from the water as a result the mud at the bottom gains its black and white layers that represent different seasons like tree rings, creating a natural geological clock.