If you want to experience some of the clearest water in the world, you can go for a dive at Silfra. You can dive (if you have a dive certification) or go snorkeling.

Silfra is a fissure created by the separation of the North American and Eurasian tectonic plates cutting through Iceland. The Silfra fissure fills with glacial water that has been filtered underground for decades through hardened, porous lava rock. The filtering process of the glacial water makes Silfra one of the clearest bodies of water on earth with up to 120 meters of visibility.

They also do pick ups from Reykjavík.

Included:
Guided snorkeling trip
All necessary snorkeling equipment
Hot chocolate and cookies after the snorkeling trip
Entrance fee into Silfra
If you choose the option with Pick Up from Reykjavík, the price includes transportation between Reykjavík and Silfra in our comfortable vans