Scuba Diving | Book Oahu Tours, Activities & Things to Do with HawaiiActivities.comExplore the underwater world of Oahu's sea life, swimming past vibrant coral reefs and playful schools of fish. Experienced divers can explore the depths of reefs and sunken ships. Introductory scuba dives are also available, complete with lessons for first-timers. Snuba is just like snorkeling, but attaches you to an air tank floating at the surface, allowing you to swim freely. For those who aren't strong swimmers, underwater scooter tours are a safe, fun, and easy way to visit the reefs.