I'm obliged to Gerard Vanderleun for linking to this fascinating video of French freediver Guillaume Néry 'surfing' the strong underwater currents through Tiputa Pass in the Rangiroa Atoll, part of the Tuamotu Archipelago in French Polynesia. Wikipedia notes:
Rangiroa offers some of the best dives in the world in and around the Tiputa Pass, which lies at one end of the one main road and runs 3.5 km to the Avatoru Pass. Sedentary common bottlenose dolphins ... regularly play group in the Pass. They can be viewed from the mainland but it is also one of the few places where they can be approached in scuba diving. Because of its large size and the existence of only two passes, each high tide creates a strong incoming current while each low tide creates a strong outgoing current in those two passes. When the current is flowing inward through Tiputa Pass, about 200 shark specimens gather at the entrance to the Tiputa Pass, at fifty meters deep. Led by the strong current, sharks can remain motionless and allow divers to observe them without any difficulty. Large manta rays, green sea turtles, and humphead wrasses can also be seen. Occasionally, tiger sharks and hammerhead sharks can also be spotted. In January, large number of stingrays gather in the Tiputa Pass, as well as hammerhead sharks that feed on them.
I recommend watching the video in full-screen mode.