French freediver Pierrick Seybald interacts with a shark in the waters north of Tahiti, French Polynesia. Pierrick Seybald puts on his flippers and jumps off the boat: here in the Vallée Blanche, a scuba diving site renowned for its tiger sharks, north of Tahiti, he is almost certain to encounter some. A few black tip and white tip reef sharks, so called because of the colour of their fins, rub shoulders with hundreds of fish and two lemon sharks