Silfra

Officially known as the Silfra Tectonic Fissure, or just Silfra for short, this freshwater rift between two continents is not only geologically intriguing, it also happens to be stunningly beautiful. 

The rift sits in the gap between the North American and Eurasian continental plates, where an imperfect seam allows explorers into the watery depths an opportunity to dive towards the center of the Earth. The clear waters of Þingvallavatn Lake in the Þingvellir National Park attract divers from around the globe to experience the unique feeling of diving between worlds, where visibility is often as good as 300 feet between lava-rock cliffs. 

Even the waters in Silfra are unique. Since no rivers flow into Þingvallavatn Lake the water actually gets slowly extruded through the porous tectonic rock beneath the water's surface. This process filters the water and not only accounts for the lake's incredible clarity but also makes the lake mostly safe to drink. Pushing water through stone is not very quick no matter how porous the rock, so it takes between 50-100 years for the liquid to become part of the lake. Each drop of water in Silfra is likely over a century old.    

Photos of Silfra abound and even amateur divers and photographers find that their experience between the plates is like nothing else on Earth or in its waters.