Seltún is a geothermal area full of mud post and hot springs.

One of the most beautiful things to see at Reykjanes Peninsula, Seltún, found in Krýsuvík about 50 minute drive from Keflavik (Reykjanesbaer) or 45 minutes from Reykjavík.  Geothermal energy in Krýsuvík is primarily spread over an oblong area around 1500 meters long and 500 meters wide in a ENE-WSW direction.  The greatest concentration of surface-level geothermal energy and rock alteration can be found in the eastern hills of Sveifluháls, at Seltún and Baðstofa (in Hveragil).  Steam dominates the area and warms up the surface water, meaning both mud pots and fumaroles are a common sight.  Steam vents, Sulphur mounds and boiling hot springs can also be found.

Krýsuvík has undergone widespread colorful alterations, best seen in the multitude of mud pots and multi-colored clay deposits, which are red, pink, dark grey, grey, blue-gray, golden brown, yellow and white in color. The most common deposits are spring salts, Sulphur and gypsum.  Some haematite has also been found the area. Waster and the natural circulation.