While French Polynesia is well within the tropics, the biodiversity is not as extensive here as you would find further west. That said, sharks are definitely a major draw to Fakarava where Tetumanu Village is located. I dived the grouper spawn with Bluewater Travel and stayed at the Tetamanu Village. We had excellent weather and great diving with superior visibility on in coming tides. While the accommodations are spartan, the food is good and diving can be done straight from the cabana perched on the edge of the pass. Just to see the dozens of blacktip sharks and yard long Mouri Wrasse on the skinny flats right behind the restaurant is worth the trip alone. The grouper spawn is a spectical and I would recommend getting there at least 4 days before the forecasted spawn to make sure you catch the gathering of thousands of grouper.