David Attenborough narrates a natural history of the oceans, examining the use animals from in and around the sea make of the constantly changing areas where land meets water.

From the open oceans, millions of sea birds are forced to come into land to breed. Sea eagles steal kittiwake chicks from their nesting ledges. Turtles lay their eggs in the sand and marine mammals haul themselves out to fight on the beaches. Sea lions emerge from the kelp to give birth, while killer whales come crashing in on the surf to snatch the sea lion's young.