Rangiroa is the most popular visitor destination within the Tuamotus and is one of the best known dive sites in the Pacific. It is the second largest atoll in the world after Kwajalein in the Marshall Islands. In fact, the lagoon is so sizable that it could actually contain the entire island of Tahiti.
As a certified scuba diver myself, I can tell you that one of the main attractions is the Drift Dive through the Tiputa Pass. Divers and snorkelers are taken by boat to the ocean or outside of the reef and dropped off into the water. Participants are asked to join hands so no one gets separated. The strong, swift-moving current takes hold and carries them along rapidly back into the lagoon.
As you float by in a rush, you can view an abundance of marine life below, including gray reef sharks and perhaps even manta rays. This is repeated several times just for the fast fun of it all. And as you return out past the reef, playful dolphins may accompany you.
For non-swimmers, a glass bottom boat excursion can be arranged.