A group of men are left on a remote, uninhabited Pacific island and as they battle through the dense undergrowth, the enormity of the tasks ahead quickly dawn on them.

The group hasn't had a meal in 48 hours and hunger takes its toll as the harsh reality of island life is dawning.

With their survival hanging in the balance, the castaways lose patience with those they feel are not doing their fair share.

Three weeks into their survival experience, the group is barely getting by on a diet of snails and coconuts; Mike and Chris battle dangerous tides.

The men enter their fourth week on the island and their bodies and minds are beginning to show the strain of the experiment.

Bear Grylls visits the men at the end of their stay on the island to explore how they coped and how the experience has affected them.