Réunion is an island in the Indian Ocean, sandwiched between Madagascar and Mauritius, a thousand miles from the east coast of Africa. Despite its remote location, as a “department” of France it’s actually part of the Eurozone, and with nearly a million inhabitants and some of the lushest and most magical landscapes in the world, the volcanic outpost has a robust tourist industry.

Tourism in the area centers around the coastal regions of Réunion, but at the island’s center is one of its most extraordinary sites, a canyon that reaches nearly a quarter mile (300 meters) into the Earth, ringed by a chorus of six tall waterfalls. Trou de Fer (the “Iron Hole”) is a collapsed crater of an ancient volcano, fed by bubbling rivers and streams, but dangerous to descend.

So rugged is the terrain at Trou de Fer, and so rain-soaked most of the year, the deep chasm wasn’t fully explored until 1989. Not that climbers hadn’t tried to reach its depths—they just never made it back out. Today it is a relatively easy hike to get there, just a couple of miles of well-groomed trails with a viewing platform at the end. From the high vantage point, you can see the surrounding mountains, tropical forests, and all the waterfalls that make their way to the bottom.