Christopher Columbus spotted three mermaids off the coast of Haiti in 1493. 'They were not as beautiful as they had been painted' he wrote. They were, in fact, manatees - perhaps the least well-known of the world's mammals. Cousteau and his team of divers follow these distant relatives of the elephant on their migration through the swamps and glades of Florida. Then they undertake the dramatic and difficult task of returning a captive manatee to the wild.