Over a year, Paul Rose, Philippe Cousteau Jr, Dr Lucy Blue and Tooni Mahto explore how a unique ocean paradise, home to the greatest variety of whales and dolphins in the world, is under threat. They dive stormy seas to investigate how a giant predator, the cannibalistic Humboldt squid, is invading this sea, and search for the threatened hammerhead shark. In an extraordinary encounter, the team carry out pioneering science on one of the largest carnivores on earth: the 20-metre-long sperm whale. They explore a sunken ship with a tragic human story, and search for evidence that the Sea of Cortez is still growing, they dive along part of the San Andreas fault line. The dive is above waters heated to near-boiling point by the furnace of the inner Earth.