Can I go to Hanauma Bay without reservation?

Technically yes, but it's risky. Hanauma Bay reserves most entry slots in advance at hanauma-bay.org, but a limited number of same-day walk-in spots open at 7:00 AM each day. These slots go quickly — arrive by 6:30 AM to queue and you have a reasonable chance Tuesday through Thursday. Weekends and holidays the walk-in line fills within minutes of opening. The bay is closed Monday and Tuesday. Hawaii residents can enter for free without reservation. If you're visiting on a tight schedule, book online the moment reservations open (typically 2 days in advance at midnight Hawaii time). Without a reservation during peak season, your odds of walk-in entry on weekends are under 50%. Keep Sharks Cove or Electric Beach as backup options if walk-in entry is denied.