Groundbreaking documentary which follows a Japanese-led team of scientists as they attempt to shed light on the mysterious world of deep sea sharks. Only 50 specimens of the newly discovered 'megamouth' have ever been sighted. Over four years, scientists and film crews voyaged in midget submarines into the depths of Suruga Bay and Sagami Bay to film them. Prehistoric 'living fossil' sharks such as bluntnose sixgill sharks, goblin sharks and frilled sharks also lurk in the bay. As part of the investigation, a sperm whale carcass was placed at the bottom of the bay to attract these sharks, which were then studied and observed from the submersible vessels. Revealing in detail the previously unknown behaviour of deep sea sharks, the film unravels another of the intriguing mysteries of our planet's biodiversity. Narrated by David Attenborough.