The team ventures into one of the world's most hostile environments, the Arctic Ocean, which plays a crucial role in controlling our climate.
Expedition leader Paul Rose, environmentalist Philippe Cousteau Jr, maritime archaeologist Dr Lucy Blue and marine biologist and oceanographer Tooni Mahto head to this hostile and remote ocean, where they plan to dive beneath the polar ice cap to explore how the ice, the dominant feature of this ocean, is shrinking and how this could affect the rest of the world.
The polar bear is threatened by the retreating ice - but it is not alone. The team risks diving in sub-zero temperatures to collect samples of some of the tiny creatures that form the basis of the Arctic's complex food chain.
As the seas warm, the Atlantic walrus could be a global warming winner, in the short term, and the team attempts to find out why. And they search for a glimpse of the world's only white whale, the beluga.