A great introduction to the ocean floor for non-divers, this 48-passenger submersible dips down to 100 feet off the Big Island. It explores 25 acres of vibrant coral gardens that have bloomed on ancient lava formations. Highlights include two shipwrecks: A WWII landing craft and a sailboat nicknamed “The Naked Lady.” (Legend claims its female owner set it on fire to purge “little green men” and wound up swimming ashore with her clothes slung off.) The hour-long excursion departs from the Kailua-Kona pier and remains a popular way to share the sea’s beauty safely and comfortably for kids and less mobile travelers (the roomy sub even has air-conditioning!). Look for combo deals that include a dive on the submarine plus snorkeling or a luau.