Stora-Viti, also known as Viti crater, is circular in shape and around 300 meters in diameter. Viti is actually a water filled marr, or explosion crater, on the slopes of the Krafla volcano and part of the Krafla fissure area of northern Iceland.Its name means Hell, in reference to the violence of the eruption.It was formed during a 5-year long explosive eruption of the west side of Krafla at the beginning of the Myvatn Fires in 1724. Inside the crater is a lake. It is present year-round.The color of the water is blue. Its shade varies depending on the light. It can be aqua blue. It is due to the bacteria and elements from the geothermal activity in the area.