Some marine mammals that breathe air and nurse their young, like us, spend a large part of their days in the abyss. Scientists are now discovering that the depths reached by these ocean dwelling giants are far greater than they had ever imagined. Using tags attached to the animals, cameras in the deep ocean trenches and 3D scanning images, this film follows and illustrates a modern scientific revolution. Constructed as a dramatic progression towards the deep sea trenches – from the shallowest to the deepest – live and VFX footage show animals that are extremely rare and highlights the remarkable physiological adaptations that allow them to dive so deep.