Segment 1: Invasive Species. Jonathan travels from the St. Lawrence river to the Caribbean, looking at several of the most well-known underwater invasive species and their effect on the environment. Segment 2: The Deepest Dive. Scuba divers are typically limited to just a hundred or so feet of depth, but on this amazing dive, Jonathan explores 1000 feet down in a special submarine and meets an astonishing variety of deep-sea animals from crabs to sharks!