Panama
The two-coast pick
Two coasts in one small country — the Caribbean archipelago of Bocas del Toro and the Guna Yala (San Blas) cays, with Coiba a genuine Pacific add-on.
Panama snorkels on two oceans, and the difference matters more here than almost anywhere else in the catalog. On the Caribbean side the Bocas del Toro archipelago and the San Blas (Guna Yala) cays give you warm, shallow, coral-and-mangrove water in protected island groups; on the Pacific side, Coiba National Park is a large protected reserve with rocky reef, big marine life and much colder, more variable water. Pick a coast, not a country — the two are separate trips.