Teeming with marine wildlife, our oceans are full of fascinating stories – like that of the sperm whale, the biggest predator on earth, that lives in the Mediterranean alongside the elusive monk seal. Underwater filmmaker Thomas Behrend takes us to the habitat of the ocean sunfish with the help of a high-tech submarine camera. And while giant octopuses and manatees are the heroes of another story, a marine biologist tells us about her unique friendship with a dolphin on the Irish coast.