Silfra fissure is located in the heart of Thingvellir national park. Silfra is regarded as one of the best diving sites in the world and for a good reason; there you can find some of the clearest water in the world. The crystal clear glacier water that has been filtered through fields of lava provides more than 100m underwater visibility, which makes the site unique. The water temperature in Silfra is at a constant 2–4°which adds to this magnificent clarity of the water. It takes the water about 30–100 years to travel the 50 KM from its origin in Langjökull glacier, Iceland’s second biggest glacier.
Silfra fissure, as well as Thingvellir valley, is the result of the tectonic drift of the North American and European plates. Each year the tectonic plates in Iceland move about 2 cm apart building up tension in the surface resulting in earthquakes that form fissures and cracks around the area. Over time, these earthquakes both deepen and widen Silfra fissure.
Silfra is normally divided into three main areas; Silfra hall, Silfra cathedral and Silfra lagoon. Each sector has it own features that can only be enjoyed from underneath the surface. Silfra is about 63 meters where it is deepest, but divers are not permitted do dive deeper that 18 meters on a regular diving tour.