This film chronicles an extraordinary expedition undertaken by Canadian extreme divers and cinematographers Jill Heinerth and Mario Cyr. In Tallurutiup Imanga, also known as Lancaster Sound in Nunavut, Canada, they dive with belugas and narwhals in the open Arctic Ocean. They venture to Greenland’s Disko Bay to explore the underside of icebergs and to discover the luminescent world of algae. Back to Canada in the Naujaat region, they swim with walruses and polar bears, the supreme predators of the Arctic. Filmed in stunning 4K, Under Thin Ice brings viewers into an awe-inspiring underwater world threatened by melting ice and rapid climate change.