The legal drinking/purchasing age of alcoholic beverages is 18.
Bottles of water are readily available. Being a French territory, wine is common and easy to find. As this is a tropical island, a multitude of fruit juices from pineapple juice to coconut milk are to be found everywhere. Pineapple juice from Moorea is not to be missed! It is sometimes better to crack open your own coconut yourself and drain it for lunch. Orange juice is the states favourite drink and oranges are grown all along the coastlines.
If you're a fan of beer, the Hinano Beer will definitely be one you will like to taste and bring a few cans home.