This story originally appeared on Travelandleisure.com.
It’s the patient traveler who knows that the treasures worth writing home about usually take a bit of work to uncover.
The Hidden Beach remains one of Mexico’s most intriguing natural features—but it takes some work to get there. The intriguing beach—which is completely engulfed by a cave with a massive hole in the roof to let in sunlight—can only be reached after swimming (or kayaking) through a tunnel.
The beach is on the Islas Marietas, off the coast of Puerto Vallarta on Mexico’s western side. To get there, visitors must board an hour-long boat ride. Once they land on the island, visitors have to swim or paddle through the Pacific waters to reach the sand.
But once at the beach, there is plenty to do. There are coral reefs in the water, perfect for an afternoon spent snorkeling. The islands feature plenty of unique flora and fauna for those that wish to discover its natural side. And, of course, there’s plenty of room on the beach for sunbathing.
But the natural oddity is not quite so natural, after all. Most believe that the cave got its unique sunroof when the Marietas Islands were used as bombing practice targets by the Mexican government during World War I. At the time, the islands were chosen because they were completely uninhabited.
In the 1960s, Jacques Cousteau led a campaign to protect the islands against harmful human interference. The islands were named a national park in 2005 and are now protected lands.