To get to Culebra, about 17 miles east of mainland Puerto Rico, fly in a six- to sixteen-seater from San Juan ($60 one-way) or Ceiba ($30 to $35 one-way) on Air Flamenco or Vieques Air Link. The ferry from Fajardo is cheaper ($4.50); take a Dramamine before you go.
Flamenco Beach Campground ($20 per night) is the thrifty way to stay near one of the Caribbean’s most beautiful beaches. Bring a tent or rent one for $20 a night from Frankie at Tent City in the beach parking lot. He also has mattresses, snorkel equipment, decent coffee, and snacks. The campground maintains tolerably clean showers and toilets, but BYO toilet paper. Clean up after yourself: The campsites are close together and garbage gets around.
If you’re looking for walls, rent an apartment (from a studio to a three-bedroom) at Culebra Beach Villas (from $125). Ask for a space in the more comfortable main building. Each apartment comes with a kitchenette and a spotty satellite TV.
If beach dwelling is too remote for you, stay in downtown (if you can call it that) Dewey at Mamacita's (from $102), which has the closest thing to nightlife on Culebra. Rooms are basic—TV, A/C, relatively hot showers—but the bar is often hopping, and some rooms have water views.