boiling grey mud pot in hverir, part of myvatn geothermal area in north east iceland, close-up view

area boiling bubbling closeup colorful crack crater crevasse field fissure formation fumarole fumaroles geology geothermal grey hole hot spring springs hverarapara hverir iceland icelandic lake landmark mineral mud pot myvatn namaskard natural nature orange pond pool red rock simmering smoke soil solfataras steam sulfur sulphating sulphur vent volcanic water north east close-up view view