The stunning visibility of Iceland's SIlfra Rift.
Divers traverse the astoundingly clear waters of the Silfra canyon in Iceland's Þingvellir National Park. (Photo: nudiblue/Shutterstock)

If you've ever wanted to dive between two continental plates, there's only one place in the world you can do it: the Silfra rift in southern Iceland.

The rift and the surrounding Þingvellir National Park are part of the divergent boundary between the North American and Eurasian tectonic plates, which are moving away from each other at a rate of about 2 centimeters every year.

Snorkeling at Silfra Canyon in Iceland
In the photo above, we can see how the Silfra rift serves as a watery divergent boundary for two different tectonic plates. (Photo: Diego Delso/Wikimedia)

Fascinating tectonics aside, the underwater canyon is also distinguished for the clarity and purity of its water.

The cold, crystal-clear water found in the Silfra fissure originates from the nearby Langjökull glacier. The glacier's seasonal melt water is released into the ground and passes through porous underground lava rocks, which serves as a natural filtration system.

After several decades, the glacial water eventually reaches the underground wells of Þingvellir Lake and the Silfra fissure. As tension builds up from the tectonic plates moving away from each other, the pure, super-filtrated water from the underground wells gradually seeps out.

A diver swims through the crystal clear water of the Silfra rift.
The Silfra rift connects to larger Þingvellir lake, which is filled with the same crystal clear, scuba-friendly water. (Photo: nudiblue/Shutterstock)

Because of these outstanding features, the canyon is one of Iceland's most popular snorkeling and scuba diving destinations. Even if you aren't able to visit, you can still live vicariously through GoPro-toting divers like the one below:

Scuba divers explore the watery expanse of Iceland's Silfra rift.
The deepest point of the Silfra underwater canyon plunges 63 meters (about 206 feet), though this depth is only accessible to highly experienced divers. (Photo: nudiblue/Shutterstock)

Catie Leary ( @catieleary ) writes about science, travel, animals and the arts.