Start your 5-hour tour with a pickup from your central Reykjavik hotel or alternatively, from a central location in the city. Then, travel by air-conditioned vehicle into Thingvellir National Park, where Silfra is located.
As you travel, take in the volcanic landscapes and hear from your guide about the park’s geology and history as the site of Iceland’s earliest parliaments. Thingvellir is also famous for the rift valley between the Eurasian and North American tectonic plates: a valley becoming gradually ever wider as the plates slowly pull apart. Some of the fissures and faults between the plates, such as Silfra, are filled with clear, cold water.
On arrival at Silfra, hop out, and listen to an introduction to snorkeling in the fissure. Then, don a special dry suit over your everyday clothes to stay dry and warm in the cold water.
Learn how to use your snorkeling equipment, and enter the water via steps. Then, follow your guide on a 30- to 40-minute tour of the only place on the planet where you can snorkel between two continental plates.
Float through the intensely blue glacial waters that are famously clear for having filtered through the underground lava for 30 to 100 years. The incredible visibility — more than 328 feet (100 meters) — showcases the rocks, with their emerald plant life and algae creating beautiful colorscapes.
Swim the narrowest section known as the Silfra Big Crack, following the fissure as it widens into Silfra Hall. Gaze through the waters into Thingvallavatn Lake before entering the deep Silfra Cathedral. Float over the boulders here before finishing in stunning Silfra Lagoon.
Afterward, change out of your dry suit, and warm up with hot chocolate and cookies before your return transfer and drop-off at the Reykjavik start point.