Dive into the deep-sea wonder of the mysterious and often dangerous Silfra, Iceland

I’m in Iceland and, despite it being the height of summer, it’s no more than 15oC. The temperatures of the lakes and rivers are just above freezing, which isn’t ideal for a diver accustomed to tropical climates, but that’s the reality of diving so close to the Arctic Circle. Iceland’s position on the mid-Atlantic Ridge, a divergent tectonic plate boundary, means that it’s a hotspot for geologic activity, prone to earthquakes, volcanic eruptions and geysers. In fact, the whole of Iceland is run on natural geothermal energy.

So why am I here? The country’s volcanic activity has created one of the greatest dive locations on our planet, Silfra. Located in the Thingvallavatn lake in the Thingvellir valley, Silfra is one-of-a- kind. It’s the only place in the world where you can stand between two continental plates and, more importantly, dive or snorkel between them.

The waters of Silfra are crystal-clear and remain a cool 2-4oC all year round. Whether you visit in summer, when bright green algae add a magnificent splash of colour to the rocks, or in winter, when you can watch the sun rise at midday and see snowflakes floating on the surface, a trip here is a spectacular experience.

Despite the serene views, the dive itself can be perilous. The only way to see this dramatic sight is to join a tour and, as there have been a few accidents in recent years, Icelandic law also requires divers to have some experience using a dry suit – 10 logged dry suit dives or a training course. Despite the risks, I eagerly swap my usual diving uniform of wetsuit and board shorts for a dry suit and joined Scuba Iceland – the largest professional dive tour operator in Iceland – for an unforgettable diving experience.

Training day

On arrival at the Scuba Iceland headquarters in Reykjavik I’m greeted by Julian O’Neil, one of the finest dry suit instructors in the country. Julian comes from a military background so I know I’m in for a physical day. To complete the pre-Silfra course, guests must undergo a theory lesson followed by a quick quiz and two trial dives during which they must demonstrate the skills and emergency procedure they’ve learnt. For the trial, Julian chose a great spot on Lake Kleifarvatn, surrounded by a stunning landscape that wouldn’t look amiss in a movie. While the lake itself looks flat from the surface, underwater it’s a completely different story. Kleifarvatn is the largest lake on the Reykjanes Peninsula.

It’s incredibly deep – 97 meters at its deepest point – and, interestingly, it has no visible surface drainage, which means there are no rivers running to or from it. Legend says that the lake is inhabited by a serpent-like monster the size of a large whale. While this is a myth, one miraculous thing you’ll definitely come across while diving here is underwater hot springs, created by the lake’s position over a highly active volcanic area.

The test dives

As we enter the water, I’m expecting a real shock with the temperature, but to my surprise it is much warmer than expected. We waddle out to a depth, inflate our suits and BCDs, check we have the right buoyancy, and begin our dive. Once submerged, Julian demonstrates the techniques we need, watching over us until he’s satisfied with our ability. The lake only has a visibility of around 10 meters – leaving me to wonder if the mythological creature is watching from the darkness – so we follow a guide line attached to the lake bed which has been placed here to make the route easier for divers.

As we explore, the temperature changes, getting warmer and warmer as we approach areas of underwater geothermal activity. Bubbles of volcanic sulphur rise from the volcanic sand and the eggy smell of sulphur is almost palpable even through your mask. You can clearly see heat rising from the lake floor in a mirage-like mist, the heat surge a luxury compared to the 4oC temperatures at Silfra. You won’t find volcanic action like this like any other lake in the world, I’m told.

For our second dive, after a scenic lunch under the Icelandic summer sun, we change location to a shallower spot on the other side of the lake where I’m able to practice my buoyancy and safety skills in more depth. I leave feeling confident and ready for diving Silfra the next morning.

The Silfra dive

After an early start, I arrive at Silfra where I’m greeted by the Scuba Iceland team. My dive leader and buddy for the day is Gergo Borbely or “Geri” for short, a Hungarian instructor who has settled in Iceland following a stint teaching in the warmer waters of Thailand. We soon make our way to the pool leading to the cave’s depths. I’m starting to get excited now as I’m staring at the divider between two continents, the North American plate on my left and the Eurasian plate on my right.

From the entrance, it’s a short 30-meter swim into the Silfra Hall, which leads into a striking system of caves with depths of up to 45 meters. Here we enjoy a stunning swim over and under rocks and boulders as we make our way through the network. Next, we embark on a challenging 200-metre swim to Silfra Cathedral, a breathtaking section of Silfra. The fissure is about 20 meters deep and 100 meters in length and the visibility is so clear that divers and snorkelers can see right across it. Gazing through this section, where the lava rock walls fall straight down on either side, is the most dramatic view of the day.

At the end of the cathedral, a sand slope emerges where the current picks up and tries to lead swimmers straight into the lake. Here, we need to be careful not to miss the left turn into the lagoon, as it would be difficult to turn back and fight against the current. The Silfra lagoon is a highlight for many divers and snorkelers because it’s the place where the visibility is clearest. From the entrance into the lagoon to the other side, a distance of 12- metres, our vision is completely undisturbed. It’s a captivating sight.

Despite the cold temperature of the water, diving Silfra is a truly spectacular experience. After exiting the water, you can no longer feel your face and lips, but while the cold quickly vanishes in the warmth of the sunshine, the memories are forever.