A gaping hole in the surface of the lush green island opens onto a secret beach, with ample shade, sun, and crystal-clear water.

Playa del Amor, commonly known as the Hidden Beach, is a feature of one of the Marieta Islands, located some 22 nautical miles west of Puerto Vallarta, Mexico, at the mouth of Banderas Bay. It looks like something out of a fantasy novel: a wide, sandy cavern with the blue waters of the Pacific rushing in. The Marieta Islands is a group of uninhabited islands formed by underwater volcano eruptions. They are natural wonders, but it was something other than the volcanic activity that brought the burrowed beach to light.

It is rumored that the hole that created the Hidden Beach was a result of deliberate bombings. The Marieta Islands have always been completely uninhabited, making them ideal sites for military testing by the Mexican government. Beginning in the early 1900s, weapons and artillery were tested on the Marieta Islands, a safe distance from Mexican citizens but not so safe for Marieta topography. Test bombs are the known cause for many caves and rock formations on the island, possibly including the Hidden Beach.

In the 1960s, scientist Jacques Cousteau led a protest against harmful human activity on the islands. In 2005, the islands were finally named a national park, Parque Nacional Islas Marietas, making swimming, kayaking, sunbathing, and other forms of recreation the only activity, and prohibiting hunting and fishing around the islands. Also, later on, the park was designated as a UNESCO MAB Biosphere Reserve. Extensive military testing damaged flora and fauna on the island for decades, but many years of peace have replenished the islands’ pristine waters and marine life.

The Hidden Beach is invisible from the outside and is only accessible through a long water tunnel that links the beach to the Pacific Ocean. There is approximately six feet of space above water level, so visitors can arrive at the beach by swimming or kayaking. The islands remain uninhabited but are frequently visited by tourists who come to enjoy the diverse marine wildlife and the unique tropical Eden of Playa del Amor.