Whilst Costa Rica does not have an official national drink, Guaro is the potent alcohol distilled from fermented sugarcane that is most characteristic of the country. This dangerous beverage has very little taste but certainly packs a punch, the impact of which is most prominent the following day... you have been warned!
The German presence in Costa Rica has given rise to several very good and inexpensive beers - Bavaria and Imperial are especially popular. Local wines are generally made from berries rather than grapes and are probably best avoided if you're not accustomed, however, it is possible to get a good Argentine or Chilean bottle at a reasonable price.
Of the non-alcoholic variety, fresh exotic fruit juices and Horchata (a rice based beverage) are widely available and deliciously refreshing. If you are visiting Costa Rica's Guanacaste province you may also come across Chan, an unusual drink made from seeds.
Unfortunately, just like seafood, Costa Rica's best coffee tends to be exported and Ticos enjoy the weaker, less expensive varieties with a lot of sugar. For a typical hot drink try Agua Dulce, a warm beverage made from melted sugar cane which can be drunk with lemon or milk.