Snorkelling Silfra: Between Two Continents in the Clearest Water on Earth

Silfra is a fissure in Thingvellir lake where the Eurasian and North American tectonic plates are slowly diverging. The crack between the plates is filled with glacially filtered water so pure that underwater visibility reaches 100 metres — the clearest freshwater in the world for diving and snorkelling. The water temperature is a constant 2 to 4°C year-round, regardless of season or air temperature. You can reach out and touch both plates simultaneously. This is one of the bucket-list experiences of Iceland and one that is accessible to non-swimmers and beginners with appropriate equipment.

What the Experience Involves

Silfra tours are operated by licensed guides from Thingvellir National Park. All operators provide dry suits — full-body waterproof suits that keep you dry inside despite being submerged, worn over your own thermal layers. The water temperature is too cold for a standard wetsuit experience without significant discomfort. In a dry suit, the cold is noticeable at the face and hands (gloves provided, but thin) but the body remains comfortable throughout.

The snorkelling route follows the fissure from the entry point at Silfra Hall through a narrow channel into the gradually widening Silfra Cathedral section — the most dramatic part, where visibility is greatest and the walls of the fissure are widest apart. The total route is approximately 300 metres and takes 30 to 45 minutes. No swimming experience is necessary — you float in the dry suit throughout.

Scuba Diving

Silfra is one of the world's most famous dive sites. The same fissure that snorkellers travel through on the surface is dived to depths of 22 metres at the Silfra Cathedral section. The 100-metre visibility makes it unlike any other freshwater dive site. Scuba diving requires Advanced Open Water certification or equivalent. Dry suit certification is required or must be obtained via a prerequisite confined water session. Book dive tours well ahead in summer.

Practical Details

Tours depart from Thingvellir National Park, 45km from Reykjavik. All equipment provided. Book in advance — popular time slots fill quickly, particularly in summer. January to March offers the fewest visitors and identical water conditions to summer.

The Tectonic Context

Silfra is a fissure in the rift zone between the North American and Eurasian tectonic plates — the two continental plates that are spreading apart at approximately 2.5cm per year. The fissure is filled with glacial meltwater that has filtered through the Langjökull lava field for 30 to 100 years, removing all particulates and producing the extraordinary 100-metre visibility. Swimming in Silfra is swimming in the gap between two continents — touching the rock walls on both sides simultaneously means one hand is on the North American plate and one hand is on the European plate. This is not a marketing conceit but a geologically accurate description. The clarity of the water — which appears almost supernaturally blue-green — is what makes Silfra one of the world's top ten diving and snorkelling locations.

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