Siberia is one of the coldest regions in the world, and the effect this has on the land is dramatic. Every winter, the mighty Lena River freezes, but as spring arrives, the rising temperatures cause an incredible change to take place in what is known locally as Redahoto — the Great Thaw. What begins as small cracks soon turns to chaos as the river becomes a raging torrent and huge blocks of ice pile up until they crash over the riverbanks. Despite the devastation, the Great Thaw is also an important lifeline that irrigates farmland that would otherwise remain parched and nurtures a forest the size of Australia. Predicting exactly when and where the Great Thaw will begin is almost impossible, but that is the challenge a team of Japanese filmmakers have set themselves. Join Great Nature on a quest to unravel the secrets of one of the earth’s most dynamic hydrological marvels—the Great Thaw.