Southwest of Lake Kleifarvatn on the Reykjanes Peninsula lies the high temperature geothermal field of Seltún in Krýsuvík. Sulphuric water and gases have created colorful deposits, the soil is colored in green, yellow and red colors. Visitors can wonder at hissing solfataras, fumaroles and boiling mud pots, where the soil is mixed with acid. Be careful not to leave the marked path because the water, mud and steam are dangerously hot. Sulfur was once mined at Krýsuvík and there is a distinctive smell of sulfur in the air—like rotten eggs but if you can ignore the stench, the geothermal area is a real delight.