Segment 1: Artificial Reefs. In the Florida Keys, several ships have been sunk intentionally as artificial reefs to provide habitat for fish and entertainment for scuba divers. Jonathan visits three wrecks of different ages to see how fast these wrecks turn into reefs. Segment 2: Free Diving with Karol Meyer. Jonathan travels to the island of Bonaire to take a course in freediving from Karol Meyer, a world-champion freediver. Soon he learns how to hold his breath and dive-with no scuba tank!