Iceland lies at the border between the Eurasian and North American tectonic plates, which are moving away from each other at the rate of 2 centimeters per year.
In the late 18th Century, one spot in the gap known as the Silfra fissure formed. It gradually filled with water from a nearby glacier. The resulting lake, which is called Þingvallavatn, is world-renowned by scuba divers for its crystal clear waters.
Not only is the scenery beautiful, but Þingvallavatn also gives divers the chance to be right between the two tectonic plates. Discovery reports:
According to Padi 5 Star Dive Center, which operates tours of the park, the lake's crystal clear water comes from a nearby glacier. As it travels to the lake, the water must pass through porous volcanic rock, which effectively filters out impurities. Padi claims that divers can drink the clean water, saying that it is "as pristine as water can get."
You can see visually stunning videos of the Silfra fissure at Vimeo.
-via Jonah Goldberg