Shark Island with Enric Sala

Secret coves where hammerheads school in enormous numbers. Coral reefs that ripple with color by day but at night turn into killing grounds for packs of whitetip sharks. Pristine waters brimming with missile-sized tuna and acrobatic dolphins in hot pursuit of gleaming clouds of fish. Cocos Island, a tiny dot in the middle of the Pacific Ocean more than 300 miles (550 km) off the coast of Costa Rica, is home to one of the greatest concentrations of predators on the planet. Dive into this carnivorous crowd in Shark Island with marine ecologist and National Geographic Emerging Explorer Enric Sala and an international team of explorers and scientists. The team traverses hundreds of square miles of ocean in search of clues to explain why so many predators congregate and why, just outside Cocos' protected waters, life largely disappears. (Source: National Geographic Wild Channel)