7 Best Sights in Cabo Rojo, Rincón and the Porta del Sol

The crescent-shape strand is the most secluded, and beautiful, of the area's beaches. It's commonly referred to as "Playa Sucia" (Dirty Beach) by locals, because of the blankets of seaweed that drift to shore during winter months. The label is rather unfitting for the white sand and turquoise waters that mark the island's southwestern corner, reachable by way of a dirt road lined with mangroves. Amenities: none. Best for: hiking; swimming.

The long stretch of sand at this beach off Route 101 is a favorite with islanders, especially on weekends. This is a Blue Flag beach, meaning it is recognized for its adherence to high environmental standards. Amenities: lifeguards; parking (no fee); showers; toilets. Best for: swimming.

The Cabo Rojo Salt Flats Interpretive Center has two-hour guided tours along nature trails and a small display about the salt flats. The best part of the center is a massive observation tower that lets you scan the outline of Cabo Rojo itself. Next to the main building is an audiovisual center where presentations on marine ecosystems and bird migration are offered.

This great beach draws large crowds on weekends to its rustic waterfront eateries and calm waters. You can rent small boats and kayaks here. Amenities: food and drink. Best for: partiers; swimming.

The area's most popular attraction is this neoclassical lighthouse, dating from 1881. The magnificent structure, built on a limestone cliff, has amazing views of the Caribbean Sea. It is open to the public, and you are free to hike around the rugged terrain or relax on La Playuela or one of the other pink-sand beaches nearby. There are no facilities here, so bring water, food, and sunscreen.

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.

Crystal clear water laps this white-sand beach that's lined with swaying palm and almond trees for shade. It's a bit hard to find and very crowded on weekends, so visit during the week or during the off-season. In high season, some kiosks with food and drink are open. Parking along Calle Buyé is free, but you'll pay $3 to park at the Buyé Beach Resort. Amenities: parking (no fee); showers; toilets. Best for: swimming; walking.