A Geothermal, Volcanic Dive Site
Kleifarvatn sits directly over active geothermal systems, and this geothermal influence is one of the most defining aspects of the dive experience.
Divers frequently report encountering pockets of warm water rising gently from the lakebed, especially in the shallow geothermal zones close to the shoreline. These vents are not large or forceful like those found in volcanic ocean environments; instead, they release a steady flow of warmer water that creates subtle temperature shifts as you move through the area.
The geothermal activity also produces thin, continuous streams of bubbles that escape from cracks and soft patches of sand. These bubbles rise slowly through the murky water, creating delicate vertical trails that catch the light from a diver’s torch.
Terrain and Visibility
Historical earthquakes—most notably the seismic activity around the year 2000—reshaped parts of the lakebed, leaving behind uneven slopes, fractured rock surfaces, and areas where geothermal heat continues to seep upward. Underwater ridges and cracks formed by land movement contribute to what many divers call a “moon-like” landscape. Visibility is often limited, but as shapes slowly emerge from the gloom, the effect can feel like exploring a quiet, submerged volcanic desert.
These geothermal zones are what attract most technical or adventure-focused divers to Kleifarvatn. The site does not offer abundant wildlife or crystal-clear views, but it provides a rare chance to observe active geothermal processes from within the water.
Low visibility
Vvisibility at Kleifarvatn is limited, and this factor shapes much of the overall diving experience. On most days, visibility averages 2–5 meters, which means objects, terrain features, and other divers only come into view when you are relatively close to them. This is largely due to the fine volcanic sediment suspended in the water, combined with the lake’s depth, stillness, and lack of glacial filtration.
On rare days when conditions are exceptionally calm and winds are minimal, visibility may extend to 8–12 meters, but these moments should be considered a bonus rather than an expectation.
Water temperature: 2-6C
The lake is cold, even though geothermal water is present. Near the hot springs you may encounter slightly warmer patches or notice a change in how the water feels, but overall you should treat Kleifarvatn as a cold-water snorkel, not a hot pool.
Best Time to Dive
Best time to dive in during the summer months. Wintertime the lake freezes completely.
Guided Tours
Several Icelandic operators offer geothermal diving tours at Kleifarvatn,
Who is it for?
Tour operators clearly state that you don’t need to be an experienced diver as long as you can swim and are comfortable in the water.