I don't believe this place! The water filling the deep crevasse called Silfra, just north of the great lake Thingvallavatn, is some of the clearest water existing naturally on this planet. Silfra means silver. With an average visibility of more than a hundred metres, this site has become world renown among sports divers and now ranks among many of the other "must-experience" places like the Great Barrier Reef, the Red Sea, Thailand and Indonesia. A visibility like this is one of those things that have to be seen to be believed. Cold and very old After some time in the water, it slowly becomes easier to comprehend the visibility, and then there is plenty of time to think about the nature of the phenomenon.
One question comes to mind again and again during the dive. How can water be so clear? Well, the explanation lies underground. Actually, the clear water has its origin far away from Thingvellir. At several locations, the glaciers of Iceland are melting, and the water resulting from this process is capable of travelling far distances underground. Naturally enough, the water is not moving very fast, which means that the journey from glaciers to Thingvellir takes some time. Scientific research has suggested that the water emerging at Thingvellir has been underway for more than 10,000 years. During this period the water has been isolated from both air and sunlight, and therefore there is almost nothing living in it.
Another important aspect of the clear water is that it is very cold. It has a year-round temperature of two to three degrees Celsius when it emerges from the countless springs, which are well hidden underground. In other words, the water in Silfra is not much warmer today than it was when it melted from glaciers just after the last ice age. Life in the water One of the reasons why the water is so clear at Thingvellir is that there is a lack of life in it. Unlike the nutrient-rich oceanic waters around Iceland, there are almost no organisms living in the water at Thingvellir. There are several reasons why oceanic water is less clear than the water at Thingvellir, and one of these is the billions of microscopic planktonic organisms, which live in oceanic saltwater.
At some locations, the visibility can be less than five metres and the water almost green from algae. The fact that there is no plankton means that there is almost no food for larger organisms to eat at Thingvellir. Thus there is generally not much life to see during the dive. Occasionally, there is a chance of meeting one of four species of Arctic trout living in the lake, but these fish get their food from hunting in the much larger lake Thingvallavatn, just south of the dive site. They are fast swimmers, which means that divers also have to be very fast to get a close look at the small colourful fish. Because of the clearness of the water at Thingvellir, it appears as if the fish are flying around like birds in the air. From Europe to America
There is more to experience than just clear water and colourful fish when diving at Thingvellir. Every continent on this planet is situated on a continental plate, which is capable of moving around. America lies on one of these plates, while Europe lies on another. These two plates are constantly moving apart from each other, creating a border known as the Mid-Atlantic Ridge. Actually, this phenomenon is what has been creating Iceland over many geological periods. The main parts of the Mid-Atlantic Ridge run at great depth along the bottom of the Atlantic Ocean, but at Iceland the ridge suddenly climbs on to land. It is possible to see long cracks in the Icelandic ground at several locations.
Silfra is just one of these cracks, which has been filled with spring water, resulting in this fantastic opportunity for diving. One of the more fascinating aspects of this phenomenon is that one end of the dive site belongs to the American continent, while the other end belongs to the European continent. This means that it is possible to swim from Europe to America and back again several times during the dive. After diving, it is fun writing postcards home, bragging about the dive from Europe to America and back again in just one day.
Drink plenty
Our dive is coming to an end. We have just spent 40 minutes in the clearest water imaginable, and I am beginning to feel thirsty. During the pre-dive briefing, I remember we were told to taste the fresh water, which is supposed to be as clean and healthy as water gets. I bring my breathing to a momentary stop, take out the regulator and open my mouth. The freezing water enters immediately and runs like a tidal wave over my tongue. I am not surprised that it tastes much better than water normally does. It is just like drinking fresh spring water from alpine mountain areas during a trek; the only difference is that today I am swimming around in it. After a while (and after plenty of water to drink), the CO2-concentration in my blood rises high, and I feel a burning urge for oxygen. The drinking is brought to an end and I fill my lungs with fresh air from the steel tank on my back, while feeling refreshed from the cold water in my stomach.
Very nice! Experience and limitations Diving at Thingvellir is more complicated than, for example, diving at coral reefs. The limiting factor is the temperature. Because the water emerges from deep underground chambers, it is very cold, and this means that any diving activities should be conducted in dry suits. It is possible to complete the dive in a wet suit, but it is not recommended. The water will cool the body down so fast that time for pleasure underwater will be limited. To get the maximum pleasure, all divers should be well equipped. If a diver never tried diving in a dry suit, it is a good idea to try a test dive before going to Thingvellir.
Another useful tip during diving at Thingvellir is to have constant control with buoyancy. The stony walls and the bottom are covered with fine, organic sediment. If a diver gets too close to the bottom or the walls, the result will be large amounts of sediment dissolving in the water and ruining the visibility. Unfortunately, it is possible for one diver to ruin the dive for the whole group this way. Please swim with caution. The depth of the dive site is no problem, and the mild currents at the site will not result in any difficulties. There is a possibility to dive in one of the many cave systems, which are widespread in the area, but always remember to ask about the local conditions. The smartest thing is to have a local guide joining the dive. Casper Tybjerg is a freelance writer and photographer living in Århus, Denmark.
For further information, contact Hédinn Ólafsson at www.diveiceland.com or on (+354) 896-2270.