Episode 4

Eight young adventurers go to extremes to help the planet. The Ocean Eight take part in two incredible wildlife projects, conducting a census of Magellanic penguins - one of the few species to live underground - and getting up close to Chile's only breeding colony of elephant seals. Sailing through the night for the first time, several of the team struggle to stay awake - especially David, who is teased mercilessly by the others.