Underwater cameraman Ken O'Sullivan sets out on a series of voyages into the North Atlantic over two years from Ireland's Atlantic coast to try to find some of the largest animals ever to live on planet Earth, blue and sperm whales. Coral reefs, 3,000 metres down in dark, cold Atlantic waters, were once regarded as the 'place of the devil'. Combining wildlife sequences of animals and behaviour filmed for the first time in any television documentary, with an enlightening, educational central narrative from passionate, fervent scientists and people who've built their lives around the ocean, these two documentaries pay homage to our earliest seafarers and investigate the health of our deep Atlantic waters.