Silfra · Iceland · Freshwater · Wall
Silfra Big Crack
The narrowest water in Silfra, both walls within reach at once
Big Crack is the first of the five sections of Silfra that divers and snorkellers can reach, and the narrowest: beside each of its three islands the fissure is only 0.5 m deep and both walls are within reach at once. It is also where the main fissure is deepest, dropping to 23 m before it runs down under the rock. Every Silfra dive starts here, at the submerged platform below the staircase.
Where it is and how deep
64.2553° N, 21.1169° WApproximate position — the dashed circle shows where the site lies; your operator's briefing has the mooring.
The dive
The dive begins on land, with a walk of about 100 metres from the Silfra parking lot to the head of the fissure and a metal staircase that ends on a submerged platform. From the platform the crack runs away ahead of you as a corridor of raw rock, 120 metres of it in this first section. The maximum allowed depth for a dive anywhere in Silfra is 18 metres, and the average works out between 7 and 12 metres, so the profile stays well above the floor.
Beside each of the three islands in the crack the bottom comes up to 0.5 metres and the walls close in far enough that divers can touch both sides at once. This is the shallowest and narrowest part of Silfra. Between those pinch points the floor drops away again: Big Crack holds the deepest water in the main fissure, falling to 23 metres before the crack heads down under the rocks and continues to a maximum depth of 45 metres, both below the 18 metre limit.
The walls through this whole section are riddled with caverns and swim-throughs at various depths, and all of them are now prohibited because the tunnels are unsafely constructed. The dive is run as an open corridor, above and between them. Past the last of the islands the fissure begins to widen and the route carries on into Silfra Hall.
Marine life and season
The sources we used don't single out particular species here.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Fair | Fair | Good | Good | Prime | Prime | Prime | Prime | Prime | Good | Fair | Fair |
Season follows Silfra: Water temperature and clarity stay constant year-round since Silfra is fed by filtered glacial groundwater; ratings track daylight hours and road access to Þingvellir, not underwater conditions.
Know before you go
- The caverns and swim-throughs opening off this section are prohibited at every depth because of the unsafe construction of the tunnels; the route stays in the open crack.
- The floor of this section falls to 23 m and the crack below it to 45 m, well past the 18 m maximum allowed depth in Silfra, so the profile has to be watched rather than followed down.
Photos from Silfra Big Crack
Jens Bludau · CC BY-SA 3.0
Dive videos
Silfra Snorkeling - part 1: starting off in the Silfra Big Crack, about 10m deep · eeviste on YouTube
Questions divers ask
How deep is Silfra Big Crack?+
The dive itself is shallow, only 0.5 m beside each of the three islands, and no dive in Silfra may pass the 18 m maximum allowed depth. The fissure is deeper than that: this section drops to 23 m before heading under the rocks to a maximum depth of 45 m.
What certification do I need to dive Silfra?+
The national park authorities require at minimum an Open Water certification from an internationally recognised agency, plus dry suit certification. In lieu of a dry suit qualification, divers may show proof of at least 10 logged dry suit dives within 2 years of the planned dive.
Sources
- Silfra's location — silfra.org
- Dive Site Silfra in Þingvellir National Park, Iceland — DIVE.IS
- Silfra dive site — PADI
Photo credits
- Clear turquoise water fills a narrow gap between frost-white and moss-covered rock. by Guillaume Baviere from Uppsala, Sweden, CC BY 2.0, via Wikimedia Commons
- Snorkelers move single file through the narrow, mossy-walled Silfra fissure. by Jens Bludau, CC BY-SA 3.0, via Wikimedia Commons
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