Oceanographer Philippe Cousteau travels to Bikini Atoll with his wife and marine biologist Luke Tipple to examine a marine environment that was affected by nuclear testing during the Cold War.

Marine biologists examine the migration of bull sharks up the rivers of Costa Rica. They look at how the young sharks evade the crocodiles that are native to the area and how this could be used to to create a shark repellent for humans.

Sharks hunt for seals off the shores of Cape Cod in Massachusetts.