Media playback is unsupported on your device

Underwater footage of marine life in Cocos Island waters

American multi-millionaires have clubbed together to fund an ultra-powerful radar system to catch fishermen plundering some of the richest marine life on the planet from a no-fishing zone round the legendary island of Cocos, far into the Pacific off the coast of Costa Rica.

They think if they can protect the seas around remote Cocos, said to be the hiding place for millions of dollars of buried pirate treasure, there's a hope of safeguarding the world's other oceanic islands which are also under threat.

Cocos sits on top of an underwater mountain chain that forces up nutrients from the deep ocean. And that makes the island's waters a globally important hotspot for sharks, as the BBC's Environment Analyst Roger Harrabin witnessed on an extraordinary night dive.

  • 08 May 2014
Go to next video: The effect of acidic oceans on coral