Diving in Verzasca River Diver in crystal clear water of Verzasca river in Ticino - Switzerland. Photograph by Marc Henauer (Not "the sea", but it fits).
“Freediving Serenity” Bronze in Divers Joel Penner, California Location: Tulum, Mexico Comment: Tulum is said to have more diving diversity than anywhere else in the world. - In memory of Richard Tedesco who loved the free dive.
Dive Hacks: Tips for Wreck Diving | Scuba Diving
The best places to swim with whale sharks - Lonely Planet