In their last few weeks on The Galapagos, the Halls family investigate the fate of the shark and also get to know the marine iguana. Monty takes Isla snorkelling with sharks, his favorite animal, and then gives a talk at his daughter's school concerning the ocean's top predator. He joins a research expedition, travelling over a 150 miles from human habitation to tag and photograph whale sharks. The work will produce invaluable data for years to come, and help not only protect Galapagos sharks, but all of our oceans.

In this episode, Monty investigates whether the Galapagos' ecosystems can cope with the demands of all the people who live and visit there. He joins a survey team monitoring juvenile sharks, and the family visit Isabella Island, explore volcanos, and start keeping chickens and growing their own food. Monty also learns how to make small scale fishing sustainable, and embarks on a terrifying night dive.

The Halls settle into their new home, where the remarkable wildlife views them as just another animal. They learn about the perils of plastics, shark conservation, and go swimming with turtles.