The Secret of Silfra | Why This Lagoon in Iceland Might be the Best Place to Dive on the Planet

The remarkable crystal clear water means that diving in Silfra feels like flying

We’ve teamed up with Seiko, who make the Prospex Diver’s watch collection, to produce a series examining one of the world’s most stunning dive sites – the Silfra Lagoon in Iceland. In this first instalment we talk to the British instructors who guide here about what makes Silfra so special, and why accurate timekeeping is essential for navigating its depths safely.


On the surface, it’s not instantly obvious what brings people here. The scrubby tussocks of grass around the lake’s edge hardly compare to rugged coastline of Croatia or the white sand beaches of Koh Phi Phi. The water is freezing, and the weather is frequently miserable – cold, windy and wet.

“The water is so clear, it feels like you’re flying above a canyon.”

But for the tens of thousands every year who brave the elements, the risk of hypothermia and even death, to dive below the surface of Silfra, these are prices worth paying. They’re gaining access to an underwater world like that’s like nothing else on the planet.

“There are very few places that have the same attraction as Silfra,” says Taz Wood, manager and dive instructor at Dive Silfra, “because the visibility is just astounding. It’s usually around 100 metres, but even on a bad day it’s 70 metres.”

By comparison in most dive sites, visibility is somewhere between 10 and 30 metres. “That’s the draw for people, to be able to see water that blue,” Taz adds.

Taz Wood checks tanks ahead of a dive, wearing her Seiko Prospex watch. Proper preparation and equipment is essential for diving Silfra safely. Photo: Elli Thor Magnusson

Her colleague, Chris Urquhart, agrees. “To be able to see from one end to the other in some places… it’s a mind-opening experience.” In fact, the water in Silfra is so transparent that people have famously suffered from vertigo when diving there. “It’s so clear, it feels like you’re flying above a canyon,” confirms Chris.

The secret of Silfra’s remarkable water lies in the mountains fifty kilometres north of the lake. As water melts off the Langjökull glacier it seeps into the porous basalt rocks. It takes 30 to 50 years to work its way through the water table, with the basalt acting as a filter. By the time it reaches the spring which feeds Silfra, almost all the impurities – minerals, bacteria, sediment – have been removed. The water is so clean, divers can take their regulators out of their mouths mid-dive and drink it.

Silfra might not look remarkable from the surface...
...but underwater, it's a whole different story. Photos: Elli Thor Magnusson

It’s not just the water quality which attracts the estimated 25,000 divers who come here every year however. Once you break beneath the surface, the geology of lake itself is incredibly dramatic. “Basically what Silfra is is a rift, it’s a crack,” explains Taz. It’s formed by the fault-line that cuts across Iceland, where the Eurasian and the North American tectonic plates meet. At various points along the fissure’s length, divers can reach out and literally touch two continents at once.

The lake is also constantly changing. “There are hundreds of earthquakes every day in Iceland,” says Taz. “I normally go there once every couple of weeks now and you’ll notice a rock’s in a different place and another lava tube or black hole has opened up, so you can see a bit further down.” The plates are moving apart as fast as an inch every year, creating new land beneath the water as they go.

“We’re not allowed to dive into any of the caves because of all the earthquakes,” says Taz, “but it looks crazy – because of the minerals in the rocks some bits are a bit gold, or a bit silver. When you shine your torch [on night dives] it’s kind of like a prism.”

The fissure is not hugely wide – at certain points divers can reach out and touch two continents at once. Photo: Elli Thor Magnusson

The clarity of the water means the light is remarkable in the daytime too, according to Taz. Especially in the most striking section of Silfra, known as the Cathedral. “If you catch the daylight right, the whole of the Cathedral gets covered in rainbows. It is stunning, the play of the light. Just astronomical.”

Diving Silfra is not completely straightforward however. “It’s not a gentle hop into the Mediterranean or anything,” says Jonathan Sherrington, a British instructor who like Taz and Chris was attracted by photos of the place. “You’re in the far north, a few degrees south of the Arctic Circle.

“The water is two to three degrees celsius, the surrounding temperature can be below zero, you’ve got hurricane strength winds [and] white out visibility sometimes. So you are in an extreme environment. You have to be prepared for the worst.”

This photo: Diving Silfra doesn't require going very deep - in fact divers are limited to 40 metres in the fissure. Below: Chris Urquhart (left) and Jonathan Sherington (right) prepare to dive, both wearing Seiko Prospex watches. Photos: Elli Thor Magnusson

As with all extreme environments you need gear that’s 100% reliable, and you need to be checking and re-checking it constantly. But according to Jonathan, the essential element to diving safely in Silfra safely is timekeeping. “The key here is timing. You’ve got the weather to contend with, you’ve got the amount of people to contend with, you’ve got other tour groups going out. Especially when the conditions are bad, when we have serious winter conditions, it’s about doing things quickly but correctly.”

It can go horribly wrong horribly quickly too. A Chinese woman in her 20s was killed in a diving accident last year, and several tourists who were snorkeling have suffered heart attacks because of the shock of the cold. However such incidents are extremely rare, thanks to the precautions and preparations put in place by experienced guides like Taz, Chris & Jonathan.

Proper time-keeping is hugely important when it comes to diving safely. Here Chris Urquhart checks his Seiko Prospex while diving in Silfra. Photo: Elli Thor Magnusson

“Silfra’s actually very safe,” says Taz. “All the companies that work here work together to train new guides on what to do if there was an emergency. We have oxygen and AED’s [defibrillators] at both the entrance and exit points, and all of our staff are emergency first response instructors.”

“The key here is timing. It’s about doing things quickly but correctly.”

There are some risks that are mitigated by Silfra’s location. As well as banning cave diving The National Park authorities, who administer the site, limit divers to a maximum depth of 40 metres, so the risks of decompression sickness are negligible. But while you won’t get the bends if you get your timings wrong here, if you want to get the most out of your dive, knowing when to go is essential.

Visitors’ experiences of it can be wildly different depending on when you visit and crucially, whether you start your dive on time. “In the summer months it gets covered in troll’s hair, which basically looks like snot, long green tendrils” says Taz, chuckling. “Now it’s all dying off because it’s coming into autumn and it looks like blobs of silver.”

Silfra changes with the seasons, meaning there's always a reason to come back. Photo: Elli Thor Magnusson

In winter the extreme latitude means there’s limited daylight. “You want to make sure you start your dive at the right time, so you get those beautiful rainbows. On Christmas Eve for example I got three hours of light.”

The fact that it’s open year-round and changes with the seasons is a major part of the lake’s magnetic attraction for Taz though. “Because it’s ever-changing you always find something new every time you go.” Which is why she, and countless others like her, come back time and time again to take the plunge in this truly unique corner of the planet.

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