Playa Flamenco spent more than thirty years as a live-fire target range, and two rusted Sherman tanks still sit on its sand. The beach is a mile-long crescent wrapped around a reef-sheltered bay on Culebra, a small island off Puerto Rico's east coast, and the water inside the horseshoe stacks up in bands — clear at your feet, milky turquoise over the sand flats, hard blue where the reef drops away. The US Navy took Culebra's public land in 1901 and shelled this coast from the 1940s until 1975, when the islanders finally forced it off Culebra for good. What the Navy left behind is strange company for a beach that TripAdvisor's travellers voted the third best in the world in 2014: the tanks, carrying a fresh coat of spray paint every few months, and a headland still closed for the ordnance buried in it.
Wade in and the ranking explains itself. The bay shelves so gently that you can walk a long way out and still be standing, over sand pale enough to throw the light back up at you, while snorkellers work the rocky points at either end where parrotfish graze the shallow reef. The green headland closing the beach is Culebra National Wildlife Refuge, created by Theodore Roosevelt in 1909 — eight years after the same president handed the island to the Navy — and every summer between 30,000 and 40,000 pairs of sooty terns nest on it, out of reach behind the closure. Nothing much stands behind the sand either: scrub hills, a lagoon, six kiosks, a campground. Most people come for the day, on the ferry from Ceiba or a ten-seat propeller plane, and go home the same afternoon.