Kleifarvatn | Iceland’s Geothermal Lake Dive

Site Overview

Kleifarvatn is a large, deep geothermal lake south of Reykjavik that offers one of Iceland’s most surreal diving environments. Set in a volcanic crater landscape, its black sand floor is pierced by eerie geothermal vents that bubble gases and release heat through the sediment, creating a "smoking" crater effect. Underwater hot springs and unique mineral formations dot the slopes, and the water holds very limited life, mainly some thermophilic bacteria and a few small lake trout. Visibility is usually low, 5 to 15 metres, and the lake is deep and dark, so it is an advanced, guide-led dive for those drawn to weird geology rather than marine abundance. The contrast of cold lake water over warm vents and the strange mineral structures make Kleifarvatn a genuinely otherworldly experience. For divers interested in volcanic and geothermal underwater landscapes, it is a highlight of the Reykjanes Peninsula and a stark contrast to the bright fissures of Þingvellir. The site is a rewarding but demanding cold-water dive that rewards preparation, good buoyancy and respect for the Icelandic environment. The site is a rewarding but demanding cold-water dive that rewards preparation, good buoyancy and respect for the Icelandic environment. The site is a rewarding but demanding cold-water dive that rewards preparation, good buoyancy and respect for the Icelandic environment.