Did you know that Iceland is the only place in the world where you can snorkel between two continental plates?

Found within the famous Thingvellir National Park Lake is Silfra, a ridge located between the North American tectonic plate and the Eurasian plate. It’s known for its vibrant array of colours and unique underwater landscapes.

Learn more about the geological history of the site, which tour to join, what to bring and so much more on this guide to snorkeling between the continents.

The Geology of Silfra

Iceland is the result of the violent forces at play between the Eurasian and North American tectonic plates, also known as the Mid-Atlantic Ridge. These two plates are moving apart from one another at a rate of around 2 cm per year. As a result, roughly every 10 years tension between the two plates is released in the form of an earthquake. 

The Silfra ridge, which is found in the Thingvellir Lake in Thingvellir National Park, is the result of a powerful earthquake that occurred back in 1789. Several fissures opened up across the Thingvellir area in 1789. However, it was the Silfra fissure that ruptured an underground spring that provided the unique snorkeling opportunity we have today.

The underground spring was filled with glacial water from the nearby Langjökull glacier. This glacial water is filtered through porous underground lava rocks for 30 to 100 years before it reaches the surface. Therefore the water here is in its purest form when it feeds into Thingvellir lake which allows for clear visibility of over 100 meters.

Because the spring water originates from warm underground sources the water at Silfra never freezes, despite the harsh winter temperatures Iceland can experience. The water temperature remains at a steady 2°C – 4°C (35°F to 39°F) all year round. 

The Silfra ridge is a dynamic snorkeling site that is constantly seeing both large and small changes. The fissure is widening as we speak, and the occasional earthquake can cause rocks and boulders to fall into the depths of the ridge. Moreover, the shifting of the tectonic plates is slowly forming new tunnels and caverns and shaping the underwater terrain.

Why Is The Water So Clear In Silfra?

There are several reasons why the water is so clear in Silfra. The first of which is that because the water temperature is at a constant 2°C – 4°C (35°F to 39°F), which is too cold for most organisms to live in. Also, the colder the water, the clearer it is.

The main reason, however, is that the water takes between 30 to 100 years to travel 50 kilometres (31 miles) through underground porous lava rocks. This process filters the water to a standard that is perhaps the cleanest water on Earth.

The gentle stream of the natural spring also makes sure the water does not stay static, ensuring that it will never become dirty. This natural filtration process results in the clear water you can see today in Silfra. On a side note, this stream also allows for an effortless snorkeling experience as the water carries you at a calm pace across the tectonic plates.

It’s the visibility of the water in Silfra that makes this snorkeling experience so unique. To put the clarity of the water into perspective, some of the most popular snorkeling and diving sites around the world boast visibility between 10 to 30 meters (32 to 98 feet). The visibility at Silfra exceeds 100 meters (328 feet), which means the visibility is over three times longer than some of the best snorkeling and diving spots in the world. Therefore the Silfra ridge is a must for anyone who enjoys snorkeling or diving.

What Can You See Whilst Snorkeling at Silfra?

Thingvellir Lake itself has a rich abundance of various fish species and is a popular destination for trout fishing. However, the fish usually don’t swim far into the Silfra fissure, which means you’ll witness a surreal underwater experience with close to no fish, crabs and other crustaceans you might expect when going snorkeling. The marine life here mostly consists of various colourful plants and algae species. Especially prevalent is the bright green “troll hair” that gently sways in the water. 

How to go Snorkeling at Silfra

If you’d like to go snorkeling at Silfra then you’ll need to make sure to sign up for a snorkeling tour. Please do not attempt to go out there by yourself - not only is this illegal, however, it can also be life-threatening without the proper gear or a skilled snorkeling guide. You can book a whole host of different snorkeling tours with us - take a look at them here. 

If you’re worried about safety, don’t be! The guides are all highly professional and trained guides who will talk you through the safety training prior to going in the water. They will also tell you more about the geology and history of the area. Don’t worry about what gear to bring either, this will all be provided as part of the tour. The only thing to watch out for is if you need to wear glasses then either wear contact lenses for the day or bring your own prescription mask. 

Snorkeling in Silfra during the Winter

The amazing thing about Silfra is that you can snorkel there all year round - even in the winter! The water maintains a constant temperature of around 2 to 4°C (35 to 39°F) and is always in motion and therefore never freezes. However, throughout the winter months, there will be considerably less daylight. Between November and February Iceland receives an average of 4 to 5 hours of daylight every day. snorkeling here in the dark would not only be pointless as you wouldn’t see much, but it can also be dangerous. Therefore there are fewer tours available throughout the winter months, however, other than this there is no difference to the tours in the summer.

The marine life inside the lake, as well as the surrounding landscapes,  will vary slightly between the winter and summer months. In the winter, the green algae don’t grow which means the colours may not be as vibrant as in the summer. The surrounding landscape will also most likely be covered in snow, creating an amazing contrast with the blackish volcanic rocks and green mosses. 

What to Wear on a Silfra Snorkeling Tour

Wetsuit vs. Drysuit

When booking a snorkeling tour, you will be given the option of choosing wetsuit or drysuit snorkeling. What’s the difference? A wetsuit is made of a rubber neoprene material that’s designed to help keep you warm when you are wet, however, it’s not waterproof. Whilst they are can feel a lot colder, wetsuits allow for more mobility in the water. We recommend wetsuit snorkeling for those who are a little more experienced and adventurous. Drysuits are fully waterproof and make it possible to swim around in water that’s 2 to 4°C, without experiencing the cold.

For those going wetsuit snorkeling, we recommend wearing swimwear. Make sure to bring warm clothes to wear before and after your tour. For drysuit snorkeling, we recommend wearing a comfortable long-sleeved shirt and long pants, as well as socks. Wear clothes that are as comfortable as possible, that will also help increase the thermal insulation of your body. 

The drysuit might feel a little uncomfortable and heavy when you first put it on, but don’t worry, this feeling will pass shortly after you’ve gotten used to the gear and you’re in the water. Your professional guide will make sure your drysuit fits correctly before you go snorkeling. They will also check the rubber strap that’s around your neck, which ensures that no water gets into the suit whilst you're snorkeling.

For both wetsuit and drysuit snorkelers, bring a towel to dry yourself off after the tour. The surreal underwater landscapes make for amazing photographs and videos as well so be sure to bring a waterproof camera or you can rent a GoPro camera from us! As fun and thrilling snorkeling is, it burns a lot of your body’s energy, so make sure to bring a good snack or lunch for afterwards.

What is the Silfra Snorkeling Tour Like?

Before going into the water your guide will help you gear up for your snorkeling adventure. They’ll also teach you about the geology and history of the area and answer any questions you may have. Once everyone is ready and everything is set you’ll head into the water with your guide in groups of around six snorkelers. Smaller groups of snorkelers mean you’ll have a lot more space and the water won’t feel overcrowded. 

As you enter the water you’ll probably start to feel the current pushing you forward. You’ll spend around 40 meters in the water, swimming over incredible underwater landscapes and witnessing the mid-Atlantic ridge up close and personal. The guide will swim with you the entire way, taking pictures of the group throughout the tour.

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Prerequisites for Snorkeling in Silfra

In order to protect individuals from potential dangers, there are strict regulations that snorkeling tours are only possible for healthy individuals. If you have any medical conditions then you may be asked to provide a physician's approval before taking the tour. Take a look at the list of prerequisites for snorkeling in Silfra below:

• Be comfortable in the water and be able to swim
• Be physically fit
• Be ready to wear a sometimes tight & constricting dry suit
• Have read, signed, and followed directions on the Silfra Snorkeling Medical Statement
• Sign the liability release form at the start of the tour
• Be at minimum 145cm (4’9) tall/maximum 200cm (6’7) tall
• Be at minimum 45kg (99 lbs) / maximum 120kg (264 lbs)
• Be minimum of 14 years of age
• Not be pregnant
• Not wear glasses, so if you have a prescription mask, please bring it with you. If not, we advise you to get contact lenses before you any snorkeling tour.

How to get to Silfra

Silfra is found in Thingvellir National Park, which is about 50km (31 miles) from Reykjavik. If you choose to drive yourself then it takes around an hour to get to a parking lot that is available for people joining a Silfra snorkeling or diving tour. The car park is nearby to Thingvellir National Park information centre, where you can find a café, shop, and toilets. If you’d prefer not to drive yourself then we also offer tours with a pick-up service which you can book here.

Things to do Around Silfra

If you’re heading out for a snorkeling tour then why not combine it with a few other sites to see in the area. Silfra is situated inside Thingvellir National Park, which by itself is a beautiful park to explore. Thingvellir National Park is also situated along the Golden Circle, which is one of Iceland’s most popular routes to see. Along the Golden Circle, you’ll find the famous Geysir, Gullfoss waterfall and many other attractions. Take a look at our guide to the Golden Circle to learn more about the beautiful landscapes and which fun detours to take. 

Not far from Silfra you can find the Secret Lagoon, which is one of Iceland’s many geothermal pools. It’s the perfect place to relax and warm up after snorkeling in 2°C water. The Secret Lagoon has been operating since the late 19th Century and boasts a water temperature of around 38°C to 40°C. If you’re interested in discovering more of Iceland’s natural hot springs and geothermal pools then take a look at our guide here.