A 300m waterfall plunging into a near-vertical canyon called the 'Hole of Iron' where sunlight reaches the bottom for only 30 minutes daily.
A geological depression
The Trou de Fer is a canyon system on Réunion Island, carved into the volcanic rock of the Piton des Neiges massif. The main feature is a vast depression, a chasm up to 300 meters (about 1,000 feet) deep, which funnels water from multiple tributaries of the Bras de Caverne River. This river system then flows out through a narrow slot canyon, approximately 3 kilometers (1.9 miles) long, known as "The Corridor".
The structure has two main parts: a large crater-like basin and the constricted slot canyon at its outlet. The geology is primarily porous volcanic rock from the dormant Piton des Neiges volcano. This porosity allows groundwater to seep through the canyon walls, creating countless small springs and waterfalls that add to the main flow. The name "Trou de Fer," or "Iron Hole," comes from the metallic sound of the water striking the rocks after its long descent, or from the rust-colored hue of the iron-rich volcanic cliffs.
A concentration of waterfalls
The primary hydrological feature of the Trou de Fer is the series of waterfalls that feed it. The Bras de Caverne River enters the system with several drops, including one main plunge of nearly 300 meters (1,000 feet) into the chasm. In total, water from at least six prominent waterfalls converges in the canyon. The combined height of the main cascades is 725 meters (2,379 feet).
At the base of the main falls, the water enters the narrow slot canyon through a turbulent feature nicknamed the "Washing Machine" because of the intense mist it generates. The flow within The Corridor can be extremely powerful and subject to rapid changes, especially during the island's rainy season. Debris jams can temporarily dam the canyon, forming deep pools. The extreme verticality and water volume made the canyon inaccessible for centuries; it was not fully explored until a three-day expedition in 1989. The first complete descent by a canyoning team occurred shortly after, in 1990.
💡Fun Facts
The total drop of the main waterfalls, at 725 meters, makes it the highest waterfall in French territory.
The main canyon is fed by a series of at least six waterfalls.
The canyon was not successfully descended and explored until 1989.
The descent for expert canyoneers is a two-day expedition that requires an overnight bivouac inside the canyon.
The viewpoint trails are accessible 24/7, but it is highly recommended to start early. Clouds often obscure the view by midday.
Admission
Access to the viewpoint is free.
Accessibility
The main viewpoint is reached via a moderate 3-hour round-trip hike from the Gîte de Bélouve. The trail can be extremely muddy and slippery, especially after rain. The canyon itself is only accessible to elite, guided canyoning expeditions. Helicopter tours offer an alternative way to see the falls.