The four-part series follows hosts Chris Packham, Liz Bonnin and Steve Backshall as they travel to different locales around the globe where marine life is coping with increasing changes. In the premiere episode, titled "Whale Sanctuary," Chris heads to Mexico, where he and the team explore the world's biggest whale nursery for gray whales and their young, while in the Great Barrier Reef, Liz observes as sea turtles hatch on the beach and make the treacherous trip back to the ocean. In the Bahamas, Steve gets up close and personal with some of the ocean's biggest predators, including Tiger sharks, and gets to meet a real-life "Shark Whisperer."