Snakes have slithered their way across the face of the earth for over 100 million years, but recently they have conquered a profoundly different environment, the ocean. Their invasion has taken place in the blink of an volutionary eye. Now over 50 species of these cold-blooded intruders have colonised the world's tropical seas. Feared by bathers and divers alike, their venom is among the most toxic of any creature. Much about Sea Snakes remain a mystery and numerous questions about them need answering. What made them abandon the land, how often do they need to breath, how often do they eat, how territorial are they, why do they return to land, are they aggressive by nature and what are their secrets to survival? The search for clues leads us to an extraordinary place that is the sea-snake capital of the world, Ashmore Reef. Here, 500 miles West of Darwin, we reveal the very private lives of these serpents of the sea.