The deep ocean that sits between the coast of Wales and Ireland acts as a marine superhighway for some of the greatest animals on earth. This is a journey into an unknown territory, that few people ever get to see.

As the water starts to warm in the summer, marine giants arrive at the Celtic deep. Some have travelled for thousands of miles to feast on plankton and abundant shoals of fish. Visitors include a group of fin whales. At 25 metres long, these majestic submarine-shaped creatures are the planet’s second largest animals. Joining them to hunt sardines are 2 metre long blue-finned tuna. These sensational super hunters have exciting courtship behaviour.

Other giants of the Celtic deep fill their huge bodies with zoo plankton. Opening their cavernous mouths, otherworldly basking sharks filter-feed their microscopic prey. Members of the shark family, these are the second largest fish on earth.

Other sharks predate in these deep Celtic waters, including the beautiful blue shark. Rarely seen, this shark is a true pelagic migratory species, travelling across the world’s oceans. Over three metres long, their beautiful blue colour is unique in the shark world. Show less