Hidden within the depths of our oceans are secrets about our past, our planet and life itself. At last, an international crack team of underwater explorers is ready to dive in - and discover them! This spectacular, surprising 8 part series combines archaeology, geology, marine biology and anthropology with all the energy and excitement of a good thriller. Each mission sees the experts living together on a dive boat, facing personal challenges and genuine jeopardy. Astonishing footage captures the full beauty of this alien world and video diaries vividly reflect the team's stresses, successes, disappointments and dangers.