Episode 3 - S1.E3

Dan Snow dives in search of underwater caves where people might have lived thousands of years ago, Steve Backshall scales the sea-cliffs to find out how the St Kildans got food when times were tough, and Kate Humble goes to find one of the wonders of the natural world. Together the team discovers why the last St Kildans left their island home less than 80 years ago.