3 affordable Caribbean islands you can visit without a passport

Perennially popular and passport-free, Puerto Rico is a beloved destination for winter-weary travelers. But here's a secret that few visitors know: Puerto Rico is much more than just one island. In fact, it's an archipelago comprising more than 100 smaller islands and cays, and U.S. citizens don't need a passport to visit .

Spending a season living on a neighboring island gave me the opportunity to visit Puerto Rico more times than I can count, including exploring many of these smaller islands that fewer visitors even know exist, let alone get to see.

Far removed from the built-up beachfronts and sprawling all-inclusives found elsewhere in the Caribbean , islands like Icacos, Culebra and Vieques offer a peek into decades past, when beaches were shaded solely by palm trees and affordable guesthouses sat between the sand and jungle-rimmed roads. After visiting at least thirty different Caribbean islands, I've come to the conclusion that these islands are some of the most memorable places to visit in the region.

• Related: The best islands in the Caribbean

Icacos

Best for: a day trip to castaway-style shores

Located just 1.5 miles off Puerto Rico's east coast, Icacos is an uninhabited island that has slowly but surely become a preferred beach day escape for those looking for white sands and very little else. 

Part of the La Cordillera Nature Reserve, Icacos is surrounded by clear, shallow waters and reefs that make it a popular snorkeling destination, including for beginners. It's just a 15-minute boat ride from the city of Fajardo, though visitors are increasingly coming all the way from San Juan for the (nearly) private island beach day experience.

Need to know:Undeveloped Icacos has no beachside facilities of any kind, so you should come prepared with everything you'll need for the day. Water taxis departing from Fajardo to Icacos start at around $50 per person, though many travelers book a catamaran cruise or speedboat ride to the island that includes food, drinks, and access to snorkeling gear for the day.  

Culebra

Best for: an unplugged, unbothered weekend beside some of the best beaches in the Caribbean

Most visitors come to the 11-square-mile island of Culebra to visit Flamenco Beach, a long crescent of white sand that regularly appears on lists of the Caribbean's best beaches . But tiny, sparsely populated Culebra has much more worth seeing, from barely touched beaches like Playa Melones, ideal for snorkeling, to sister island Culebrita, a dedicated nature reserve where turtles nest on the sands of Playa Tortuga. 

With fewer than 2,000 residents, there's not much to do here beyond grabbing a golf cart and hopping from beach to beach for what feels like a vacation tailor-made for disconnecting.

Need to know:  Culebra is accessible by ferry from Ceiba on Puerto Rico's east coast, and the trip takes roughly an hour. A limited number of advance tickets are available to nonresidents online, so book ahead when possible, especially during busy periods. Alternatively, Culebra is reachable by a roughly 30-minute flight from San Juan, with one-way fares starting around $90.

Vieques

Best for: a more adventurous vacation filled with kayaking, hiking and drives to remote beaches

Vieques is known as much for its laid-back feel as it is for its natural anomalies, from the black sands at the aptly named Playa Negra to the island's world-famous bioluminescent Mosquito Bay. 

Visitors make day trips all the way from San Juan just to see Mosquito Bay's water glow blue at night. But the largest of the "Spanish Virgin Islands "offers many more reasons to stick around. More rugged than Culebra, Vieques invites visitors to rent a 4x4 to navigate rough roads to remote beaches and explore the designated public areas of its sprawling national wildlife refuge.

Need to know:With roughly 8,000 residents, Vieques has a lot more to choose from when it comes to places to eat, play and stay on the island. Two small towns, Isabel Segunda and Esperanza, offer plenty of affordable guesthouses, plus design-minded boutique hotels like El Blok and wellness retreat Finca Victoria . Like Culebra, Vieques is also accessible by ferry from Ceiba or by flight from the capital.