Unbelievable waters! My wife and I chartered a Moorings 42'' Cat in Raitea and enjoyed all the waters surrounding Raitea, Tahaa and Bora Bora. Bora Bora is something majical. We had so much fun on the water we only came to land twice. We got off once to go to a Lagooquarium (sp?), a fenced in area of water to swim with sharks, rays and a lot of fish. And once for dinner and the show at Le Meridien (Very nice, $$$).
Ask locals where the best places are to swim with the Manta Rays...they are beautiful. As I recall, there is a popular spot on the south side of Bora Bora.
I wish I could tell you more but all the "dos" are sunsets, snorkeling and sailing...and the only "don''t" i can think of is sunburn!