Snorkelling Silfra means floating between two tectonic plates in glacier-clear water at Þingvellir. Here’s what the fissure, dry suits, water temperature and season really involve.
Few experiences in Iceland feel as otherworldly as Silfra snorkelling. At Þingvellir National Park you float face-down in a flooded rift between two tectonic plates, gliding over glacial-blue water so clear it can feel like swimming through air. This guide explains what the Silfra fissure is, why the visibility is so extraordinary, what dry-suit snorkelling actually involves, and how to fit a Silfra dip into a wider day in the Þingvellir area. One thing to be upfront about: Sterna Travel does not run in-water Silfra snorkelling or diving — we will point you to the right people for that — but we do bring you to the national park where Silfra sits.
What is the Silfra fissure?
The Silfra fissure is a crack in the Earth’s crust within Þingvellir National Park, part of the boundary where the North American and Eurasian tectonic plates slowly pull apart — by roughly two centimetres a year. Þingvellir is one of the few places on the planet where this mid-Atlantic rift sits above sea level on dry land, which is partly why the area is a UNESCO World Heritage Site: it matters for its geology as much as its history.
Silfra itself is fed by meltwater from the Langjökull glacier. That water travels underground through porous lava rock for decades before it surfaces in the fissure, emerging filtered, cold and astonishingly clear.
Why is Silfra snorkelling so special?
Water clarity
Underwater visibility at Silfra regularly reaches 80 to 100 metres. Because you are floating in filtered glacial meltwater rather than run-off carrying silt, there is almost nothing suspended in the water. The result is a luminous blue-green clarity that photographs barely do justice to.
Between two continents
In the narrow sections known as Silfra Hall and the Big Crack, the rift closes in enough that snorkellers can reach towards rock on either side. You are not literally touching two continents at once — that is a romantic exaggeration — but you are floating inside the gap between two tectonic plates, which is a fair claim to fame.
Dry-suit snorkelling: what to expect
The water in Silfra hovers at around 2 to 4°C all year, just above freezing. For that reason Silfra is a dry-suit activity. Unlike a wetsuit, a dry suit keeps water off your body entirely; you wear warm thermal undergarments beneath it, plus a neoprene hood and gloves. Most operators float you gently downstream on a mild current, so the snorkelling is relaxed rather than strenuous — though your exposed face and lips will still feel the cold.
A typical in-water session lasts 30 to 45 minutes, with extra time on either side for kitting up and warming back up afterwards. A hot chocolate at the end is something of a tradition.
Requirements: who can snorkel Silfra?
Because Silfra involves cold water and dry-suit equipment, certified operators apply firm rules. Expect requirements along these lines:
You must be able to swim and be comfortable in deep, cold water.
Minimum age is usually 12 to 14, depending on the operator.
Dry-suit snorkelling typically requires participants to be at least roughly 145 cm tall and within a set weight range, so the suit seals correctly.
You will sign a medical declaration; certain heart and respiratory conditions, pregnancy and recent alcohol consumption can rule you out.
A reasonable command of English is needed to follow the safety briefing.
Snorkelling needs no diving certification. Diving Silfra, by contrast, requires a recognised dry-suit diving qualification.
When to go
Silfra can be snorkelled year-round. The water temperature barely changes between summer and winter because it is glacial spring water, so the underwater experience is similar whatever the season. What changes is everything above the surface: long daylight and milder air in summer, frosty air and a chance of snow-framed scenery in winter. Whenever you visit, book ahead — Silfra slots fill quickly in the peak months.
Seeing Þingvellir with Sterna
Here is the honest part. Sterna Travel does not operate Silfra snorkelling or diving — that must be booked with a certified dive operator licensed to guide in the fissure. What we do is bring you to Þingvellir itself. The national park is the first stop on our Golden Circle Classic day tour, where you walk the Almannagjá gorge along the same continental rift that Silfra cuts through, before continuing to the Geysir geothermal area and the Gullfoss waterfall.
A common, practical approach is to join a Silfra session in the morning with a dive operator, then explore the wider park and the rest of the Golden Circle. If you would rather keep things simple, see Þingvellir on the Golden Circle Classic with us and arrange the in-water Silfra experience separately with a specialist.
Frequently asked questions
Does Sterna Travel run Silfra snorkelling tours?
No. Silfra snorkelling and diving must be run by certified dive operators licensed for the fissure. Sterna brings you to Þingvellir National Park, where Silfra is located, as part of the Golden Circle Classic day tour; the in-water experience is booked separately.
How cold is the water in Silfra?
Around 2 to 4°C all year. A dry suit and thermal layers keep you warm, though your exposed face and lips will feel the chill.
Do I need to be a strong swimmer?
You do not need to be an athlete, but you must be comfortable swimming and floating in deep, cold water. Operators float you along a gentle current and you wear a buoyant dry suit.
Can children snorkel Silfra?
Minimum ages vary by operator, typically 12 to 14, with height and weight limits so the dry suit fits and seals correctly. Always check directly with your chosen operator.
How long does the experience take?
The in-water portion is usually 30 to 45 minutes, with around two hours on site once the briefing, kitting up and warming up are included.
What should I bring?
Warm base layers (thermal top and bottoms), thick socks and a towel. The operator provides the dry suit, hood, gloves, mask and snorkel. Leave valuables behind and bring a waterproof camera if you have one.
