Protected from sea currents off the Gulf of Mexico and blessed with remarkable coral and marine life, Isla de la Juventud offers some of the Caribbean's best diving: 56 buoyed and little-visited dive sites here will make you truly feel like a castaway. The dive sites are an underwater adventure park of everything from caves and passages to vertical walls and coral hillocks, while further east, in an area known as Bajo de Zambo, you can dive to the remains of some 70-odd shipwrecks.
The International Diving Center, run from Marina Siguanea just south of Hotel Colony on the island's west coast, is the center of diving operations. The establishment has a modern on-site recompression chamber along with the services of a dive doctor. It's from here that you can be transported out to the National Maritime Park at Punta Francés.
Boat transfers to Punta Francés take 90 minutes and deliver you to a gorgeous stretch of white-sand beach, from which most main dive sites are easily accessible. The cream of the crop is Cueva Azul (advanced), a trench of cerulean blue with a small cueva (cave) about 40m down, followed by Pared de Coral Negro (intermediate), a wall of black coral. You'll see lots of fish, including tarpon, barracuda, groupers, snooks and angelfish, along with sea turtles.
Diving costs start at CUC$43 for one immersion. Inquire at Hotel Colony about diving and other nautical activities on offer first.