The public beaches in Hawaii prohibit drinking alcoholic beverages. However, you can still enjoy a cocktail or a glass of wine or beer at Hawaii's waterfront restaurants and beach bars.
Hawaii Beach Rules
Drinking and possessing alcohol is not permitted on the public beaches in Hawaii. If you stay in a home with a private beach, you are welcome to enjoy an alcoholic beverage. Your hotel or resort may allow you to enjoy drinks at the pool in plastic cups; check at the front desk or read their policies before you do so. Remember that the drinking age is 21 in Hawaii, and no one under that age is permitted to consume or possess alcohol anywhere.