North Atlantic: The Dark Ocean

In wintertime, the waters of the North Atlantic are particularly treacherous. Monstrous storms can flare up at any moment. But as underwater cameraman Ken O'Sullivan discovers, these storms are a huge source of fertility in the ocean. He also meets a group of Minke whales lunge-feeding on shoals of sprat, and travels to Norway in search of herring.

Fin whales are the second largest animal ever to have lived. But almost nothing has been documented about their migration routes, especially for breeding. Ken O'Sullivan voyages 1000 miles out to the Mid-Atlantic ridge in search of the enigmatic creatures. Here he finds bountiful life and gains a deeper understanding of the ocean’s eco-system.

From its surface waters to its deepest depths, the North Atlantic contains an incredibly diverse range of marine life. In the final episode of this fascinating nature documentary, underwater cameraman Ken O'Sullivan tries to capture the ocean’s unique wonders and witnesses more than thirty basking sharks engaged in a courtship ritual, possibly the largest group ever captured on camera.