The Big Island is the youngest island, and it shows underwater: lava coastline, minimal runoff, and the clearest water in the state. It also splits into two different snorkeling worlds — the dry Kona side with the famous bays, and the rainy Hilo side with quiet, turtle-rich parks almost nobody writes about. Both are below.
Kona side
Kealakekua Bay (Captain Cook) is the spot most firsthand reports call the best snorkeling in Hawaii — reachable only by boat tour, permitted kayak, or a steep hike. Two Step gives you a taste of the same south-Kona clarity free from shore, stepping off a lava shelf into a coral drop-off. Kahalu’u Beach Park is the beginner spot: shallow, lifeguarded, turtles nearly guaranteed. And after dark, the manta ray night snorkel is the island’s signature experience.
Hilo side
Richardson Ocean Park (black sand, lifeguards, resident turtles) and Carlsmith Beach Park (a lagoon behind a natural rock wall) are calm, free and uncrowded — the reward for staying on the quiet side of the island.
Full guides — Captain Cook’s three access routes, Two Step’s entry technique, manta tour comparison — are publishing now.