We're diving in an area called Muri Muri, just north of Bora Bora, and nearly as soon as we get in the water, our dive master, Benoit Gratas, introduces us to a Hawksbill Sea Turtle — like Crush, a character in Pixar's "Finding Nemo" — and shows us how to feed him a piece of sea sponge by hand — 70 feet under water.