Over 100 people drown each year in New Zealand, and Bear must cross a raging river on a tree trunk to head toward civilization. On his journey to safety he runs out of water, is forced to climb up active volcanic ranges and scale down a waterfall.

Bear Grylls -- lasso in hand -- crosses a raging river and descends rock pinnacles in Utah.

Bear returns to Iceland to demonstrate the challenge of surviving its many pitfalls. His trek begins on an ice cap covering an active volcano, where food sources are scarce and travels down towards a civilization with swollen rivers between him and safety.

This week Bear braves the remote wilderness of New Zealand's South Island, crossing the country's tallest mountains and attempting to start a fire with wood that is soaking wet.

Bear brings along a companion, actor Jake Gyllenhaal, to test how he measures up to unpredictable and unforgiving Mother Nature.