From saving lives to risking his own: Dr Richard Harris dives into the unknown.

In the remote wilderness of New Zealand’s South Island, “Harry” Harris and a close-knit team of divers set out to push human limits in the Pearse Resurgence — one of the most dangerous underwater cave systems on Earth. Using hydrogen as a breathing gas, a volatile and experimental method, they face life-threatening cold, crushing depths, and the ever-present possibility of disaster.

Harris, named Australian of the Year for his pivotal role in the 2018 Thai cave rescue, knows both the risks and rewards of diving. But as he prepares for this descent, he is forced to ask: what are the costs of passion, and why do we chase the unknown?

Award-winning director Jennifer Peedom (Sherpa, Mountain, River) and co-director Alex Barry capture this daring expedition with Harris’s own extraordinary cave footage, Benjamin Dowie’s breathtaking cinematography, and a stirring score by Antony Partos (Animal Kingdom). The result is a gripping, SXSW-selected documentary that dives into both the exhilaration of exploration and the profound human drive to go deeper.