SIlfra fissure is a crack in the earth ripped open by the divergence of the North American and Eurasian tectonic plates, making it the only place in the world where you can dive between two continental plates. Comprised of near freezing glacial melt water from the Langjökull ice cap that percolutes 50km through porous lava rock from the Skjáldbreiður volcano, which acts as an acquifier. Thie water takes 30 -100 years to reach Silfra, resulting in in some of the most crystal clear waters in the world -with visibility up to 100m!