Mama Juana: a mixture of bark and herbs left to soak in rum, red wine and honey.
Additionally, other imported drinks are available for purchase--at least in the towns and cities--they might not be as readily available out in the countryside.
Do not drink tap water! Locals, even in the most rural areas, will either boil their water or purchase bottled water. Eating salads or other food that may be washed in tap water is not advisable. Ice is a bad idea as well, except in luxury hotels and restaurants which produce ice from bottled water. If you plan on cooking or washing dishes for longer stays, it is a good idea to rinse everything with bottled or boiled water before use.