Picture this as the world's biggest open-air aquarium. You go here to see fish, and fish you'll see. Due to their exposure to thousands of visitors every week, these fish are more like family pets than the skittish marine life you might expect. An old volcanic crater has created a haven from the waves where the coral has thrived. There's an educational center where you must watch a nine-minute video about the nature preserve before being allowed down to the bay. The bay is best early in the morning (around 7), before the crowds arrive; it can be difficult to park later in the day. No smoking is allowed, and the beach is closed on Tuesday. Hanauma Bay Dive Tours runs snorkeling, snuba, and scuba tours to Hanauma Bay with transportation from Waikiki hotels. OPEN: Wed.-Mon. 6-7.