Strýtan Hydrothermal Cones

Akureyri · Eyjafjörður · Iceland

Strýtan is one of those dive sites that feels like it should not exist. Rising from the dark floor of Eyjafjörður in northern Iceland, these hydrothermal chimneys are geological formations of global rarity — the only known shallow-water geothermal vents in the world accessible to divers. Similar structures exist along mid-ocean ridges in the deep ocean, but at depths of thousands of metres where only submersibles can reach. At Strýtan, the top of the main cone sits at just 15 metres, placing one of the planet's most extraordinary geological phenomena within reach of a certified recreational diver. The main Strýtan chimney rises approximately 55 metres from the seafloor at 70 metres to its summit at 15 metres, a towering column of mineral deposits built up over some 11,000 years by water heated to 72 degrees Celsius deep in Iceland's volcanic bedrock. As this superheated freshwater meets the 3-degree Arctic seawater, dissolved minerals precipitate instantly, adding fraction by fraction to the cone's mass. The visual effect is mesmerising: shimmering curtains of warm water billow upward from vents on the cone's surface, distorting the light like a desert mirage turned vertical and underwater. I descended onto the summit of Strýtan on a still July morning, and the experience remains one of the most surreal of my diving life. The cone's surface is textured with white and rust-coloured mineral crusts, dotted with small vents that release streams of hot water you can feel through your drysuit gloves. Cod and wolffish patrol the cone's flanks, and sea anemones and starfish colonise the mineral surface. A smaller cone called Arnarnesstrýtan lies closer to shore at 15 to 25 metres and offers an equally atmospheric dive with better light penetration. Diving Strýtan requires advance planning and the right operator. The site is a protected nature reserve, and all dives are conducted through the Strytan Divecenter in the village of Hjalteyri, operated by Erlendur Bogason, who has dedicated decades to studying and protecting these formations. Diver numbers are strictly limited to prevent damage to the fragile mineral structures. Akureyri, Iceland's northern capital, is a 20-minute drive away and offers domestic flights from Reykjavik. The water temperature ranges from 2 to 8 degrees depending on season, and a drysuit with appropriate thermal protection is mandatory. Strýtan is diving at the intersection of geology, biology, and wonder — a site that reminds you how much of this planet remains astonishing.