2 Best Sights in Rincón and the Porta del Sol, Puerto Rico

Protected by the U.S. Fish and Wildlife Service, this uninhabited island—about 20 km (13 miles) off the coast of Rincón—is home to lizards, rats, and rhesus monkeys, first introduced in 1967 from Cayo Santiago. Among divers, it's known for abundant reef and fish life. The main draw here is "Candyland," a rocky bottom that rims the island and slopes to 120 feet. Long tunnels and caverns covered with purple hydrocoral distinguish one formation known as Yellow Reef. With visibility of 150 feet, this is also a popular snorkeling spot. Other sites have plentiful fish and coral in shallower water just off Rincón's shores.

About 80 km (50 miles) off the Morrillos Peninsula, at the island's very southwestern tip, Mona Island sits brooding in the ocean. Known as the "Galápagos of the Caribbean," the 14,000-acre island has long been a destination for adventurous travelers. It's said to have been settled by the Taíno Indians and visited by both Christopher Columbus and Juan Ponce de León. Pirates were known to have used it as a hideout, and legend has it that there is still buried treasure to be found there. Today, however, Mona's biggest lure is its distinctive ecosystem. It is home to a number of endangered species, such as the Mona iguana and the leatherback sea turtle, as well as a number of seabirds, including the red-footed booby. Off its coast are reefs filled with 270 species of tropical fish, black coral, and purple sea fans. On land, you can explore 200-foot cliffs on the island's north side or an abandoned lighthouse to the south. The only way to get here is by boat—planes aren't permitted to land. Several tour operators in Joyuda, Boquerón, Mayagüez, and Rincón offer camping trips and will help arrange permits from the Puerto Rico Department of Natural and Environmental Resources.

You need to reserve at least a few weeks ahead for an overnight stay.