The extraordinary story of the group of Finnish divers and their secret mission to bring the bodies of their two friends home from deep inside an icy cold underwater cave system. The two men drowned in February 2014 inside the cave system in the Plurdalen valley in central Norway at a depth of more than 100 metres.
Norwegian police concluded a recovery operation was too risky, but the men's diving friends mounted a secret mission to bring them home. It's the subject of a new film Diving into the Unknown.
Kathryn Ryan speaks with diver Vesa Rantanen and film director, Juan Reina.