Seltún geothermal field within Krýsuvík volcanic system. his area is situated next to Krýsuvík in direction of lake Kleifarvatn (Route 42) and at the foot of Sveifluháls hyaloclastite ridge. It is a geothermal high temperature area, hydrothermal alteration has led to a multicolored environment. Here solfataras, fumaroles, mud pots and hot springs are formed, the soil is coloured bright yellow, red, and green caused by iron oxidation, sulfur and calcite precipitation. The sulfur deposits were mined in 1722–1728 and in the 19th century. German scientist Robert Bunsen visited the site in 1845 and, based on research there, proposed a hypothesis on formation of sulphuric acid in nature. The area can be visited on footpaths. A small hut provides services to the traveler.