Silfra
Þingvellir National Park, Iceland




Photos: Diego Delso (CC BY-SA 4.0), Diego Delso (CC BY-SA 4.0), Josephyoon4 (CC BY-SA 4.0), Diego Delso (CC BY-SA 4.0)
- Distance
- The Cathedral, about 100 m long
- Water
- 2 to 4 C all year
- Depth limit
- 18 m for divers
- Snorkellers
- Age 12 and over, with a guide
Why go
Silfra is a flooded crack in the lava of Þingvellir, in the rift where the North American and Eurasian plates are pulling apart by about 2 cm a year. The water is meltwater from Langjökull, Iceland's second largest glacier, about 50 km to the north, and it spends somewhere between 30 and 100 years seeping through the porous rock before it rises in the fissure's springs. That long filtering is why the water is so clear: you float face down over pale rock walls and look a long way down and a long way ahead. It is the coldest swim on this list and one of the strangest anywhere, and most people come out of it shivering and keen to go again.
The route
The usual snorkel drifts with a slight current from the entry steps through the narrow fissure and into the wider sections. The Cathedral, about 100 m long, is the part people remember, because you can see from nearly one end to the other. It finishes in the shallow lagoon, about 120 m long, where operators say you may have to swim against a gentle current near the end. Snorkellers spend about 30 to 40 minutes in the water. Divers follow the same rift, and the park caps diving at 18 m and forbids entering caves or other overhead spaces.
When to go
Silfra is open all year and the water stays at about 2 to 4 C whatever the season, so the time of year changes the air and the light rather than the swim. Summer gives long days and mild air for warming up afterwards; winter tours run in the short daylight and you get out into frost.
Getting there
Þingvellir National Park is about 45 to 60 minutes' drive east of Reykjavík. Most snorkel tours offer either a meeting point at the Silfra car park or a transfer from the city. The park is reached on the Golden Circle road, so it pairs easily with a day of driving.
Permits and booking
The park's rules apply to everyone: never enter alone, always with a buddy; divers need a certificate equivalent to Open Water, plus a dry suit certificate or proof of 10 dry suit dives in the last two years; snorkellers need a dry suit or a thick, close fitting wetsuit with hood, gloves and boots. Snorkelling is sold as a guided tour, with a guide in the water the whole time. Operators set the minimum age at 12, ask for a height of at least 150 cm and a weight of at least 45 kg, and everyone signs a medical statement; people aged 60 and over need a doctor's signature. Check the current permit fee with your operator.
How hard it is
Physically easy, mentally bracing. The dry suit keeps your body dry, but your face and hands meet water close to freezing. You must be able to swim without a life jacket or other aids, and the current near the end needs a few steady kicks.
Where to sleep
The park runs campsites at Þingvellir, and there are guesthouses and hotels around the Golden Circle. Many people simply stay in Reykjavík and go out on a morning tour.
Tips
- Wear thermal layers and thick socks under the dry suit; the operators provide the suit but warmth comes from what you wear inside it.
- Walk the rift path above Silfra afterwards to see the same fissure from dry land.



































