Guillaume embarks on a Tahiti-Mo’orea crossing to reach new South Pacific islands on his route that will enable him to report on an essential component of sustainability in the region: coral reef ecology. He makes a first stop in Mo’orea to converse with scientist Cody Clement from Berkeley University, before heading to Bora Bora to visit French scientist and entrepreneur Denis Schneider’s sea experiments. Both coral gardeners are working on innovative methods to revive coral reefs, to help them gain maturity more efficiently in warming waters.