Puerto Rico: Discover a Caribbean Paradise in the U.S.

Start a tour of the bustling city in historic Old San Juan, where Spanish history fills the 16th century cobblestone streets. Here's you will find the impressive Castillo San Felipe del Morro (also known as "El Morro"), a fortress built by the Spanish conquistadors to protect the harbor, towering 43 meters over the sea.

Across the city is the equally well-preserved Castillo San Cristobal, which was built to guard the eastern entrance to San Juan. Wander between the two massive forts to see the wrought iron railings and brightly colored buildings.

Another architectural and historical highlight is the Cathedral of San Juan Bautista, where the remains of Juan Ponce de León, who discovered Puerto Rico, are interred. Keep an eye out for street vendors selling everything from fresh coconuts to sweet pastries that you can enjoy at Parque Las Palomas ("Pigeon Park") with its sweeping views over the bay and Paseo de la Princesa.

Heading south from the old city are the neighborhoods Condado and Isla Verde, where golden beaches are lined with hotels, shops and restaurants. Condado offers walkable boulevards filled with clubs and nightlife and some of the island's best dining. Isla Verde, just minutes from the international airport, has two of the top resorts in San Juan: The Ritz-Carlton and the iconic El San Juan Hotel.

With some 365 beaches, Puerto Rico offers a beach for every day of the year. A few favorites include palm-ringed Luquillo Beach, which is known as the "Sun Capital" of Puerto Rico. The water here is protected by a reef, which makes it a top choice for snorkelers, as well as people who appreciate the calm tides. Nearby is a popular array of food stalls, serving everything from piña coladas to fried seafood.

Further down the coast, luxury resort El Conquistador features private Palomino Island, a great place for swimming, snorkeling and horseback riding. Colorful fishing boats line Aguadilla's picturesque – and surprisingly calm – Crashboat Beach on the island's west coast. (Its name comes from its former use as a military port to rescue U.S. Air Force crews that "crashed" during training runs.)

On the southwest tip of the island, the beautiful soft white sand and crystal waters of Buye Beach are complemented by neighboring Cabo Rojo's pink cliffs. It's popular with locals, but not well known among travelers. Rincon, on Puerto Rico's west coast, is a surfer favorite.

Located just 43 kilometers southeast of San Juan, El Yunque is the only rain forest in the U.S. National Park Service. The landscape is filled with waterfalls, hiking trails, chirping coqui frogs and colorful parrots. Zipline tours give you a view of the tops of trees as you fly from a wire 24 meters off the ground.

Bioluminescent bays, where water glows at night, are another highlight. You can witness the natural phenomenon, created by micro-organisms that light up when agitated to create glowing rivers of light, on the southeast coast in Fajardo, on the southwest corner of the island at La Parguera and at Vieques' Puerto Mosquito. You can also explore deep underground at the Cavernas del Rio Camuy; it's 220 chambers are filled with otherworldly rock formations.

Discover even more to see and do in another USA Caribbean paradise the U.S. Virgin Islands.