Trou de Fer

{{Short description|Canyon on Reunion Island}}

{{Use dmy dates|date=April 2025}}

File:La Réunion Trou-de-Fer3.jpg

File:Trou-de-Fer-hélico.jpg

The Trou de Fer ("Iron Hole") is a canyon on Reunion Island, off the coast of Madagascar in the Indian Ocean. The primary river flowing through the gorge, which is up to {{convert|300|m|abbr=on|-2}} deep, is the Bras de Caverne River, a tributary of the Rivière du Mât. The canyon has two distinct parts: a large crater, which is fed by six prominent waterfalls, and a narrow slot canyon at its outlet, which constitutes most of the canyon's length. The canyon starts at the waterfall of the Bras Mazerine stream and after some 1.4 – 1.8 km from the left side joins the main Bras de Caverne stream.{{cite web|url=http://www.wondermondo.com/Countries/Af/IndianOcean/Reunion/TroudeFer.htm|title=Trou de Fer canyon and waterfalls|publisher=Wondermondo}}

The Bras de Caverne River enters the canyon with a waterfall about {{convert|200|m|abbr=on|-1}} high. This drop is usually dry or has very little water,{{cite web|url=http://www.crystalcanyons.net/Pages/TripReports/ReportImages/ReunionIslandPages/A7.htm|title=The First Drop in the Trou de Fer|publisher=crystalcanyons.net|last=Hart|first=John|date=October 2002|accessdate=2009-07-13}} but between that and the next, {{convert|180|m|adj=on}} drop, springs feed the river, which drops over this then drops over a final {{convert|300|m|adj=on|-2}} undercut cliff into the Trou de Fer in a narrow plume of water.{{cite web|url=http://www.world-waterfalls.com/waterfall.php?num=173|title=Trou de Fer, Cascades de|publisher=world-waterfalls.com|work=World Waterfall Database|last=Swan|first=Bryan; Goss, Dean|accessdate=2009-07-13|date=13 April 2006}}

File:Trou-de-Fer.jpg

Directly to the left of this waterfall, another stream drops over the cliff, which is undercut to an extent that its lip has over {{convert|200|m|abbr=on}} of empty space between it and the canyon floor, of approximately the same height in two channels, and slams onto a ledge before emptying into the same pool as the Bras de Caverne waterfall. This waterfall is not as high, and has a smaller water flow. It is fed by several other falls streaming off the cliffs above it. Further to the left, at about twice the distance from the first falls to the second, another large stream plunges into the canyon.{{cite web|url=http://www.crystalcanyons.net/Pages/TripReports/ReportImages/TrouDeFer/T2.htm|title=The Route from the Second Cascade to the Bottom|publisher=crystalcanyons.net|last=Hart|first=John|date=October 2002|accessdate=2009-07-13}}

In total, there are at least six waterfalls feeding the canyon. At the base of the canyon, a separate slot canyon, or "The Narrows", begins. The water from the Bras de Caverne waterfall and the waterfall to its left drain into the slot canyon at a 90-degree angle, through a waterfall known informally as the "Washing Machine".{{cite web|url=http://www.crystalcanyons.net/Pages/TripReports/ReportImages/TrouDeFer/T5.htm|title=Approaching the Washing Machine|publisher=crystalcanyons.net|last=Hart|first=John|date=October 2002|accessdate=2009-07-13}} The name stems from the mist it generates, which drenches people who stand near the base of the falls.{{cite web|url=http://www.crystalcanyons.net/Pages/TripReports/TroudeFer.htm|title=Canyoneering Reunion Island: The Trou de Fer|publisher=crystalcanyons.net|last=Hart|first=John|date=October 2002|accessdate=2009-07-13}}

The slot canyon, or "The Corridor", extends for about {{convert|3|km|abbr=on}}, and is said to be commonly dammed up by debris jams to form lakes, including the "Lake of the Eel". Many springs flow through the porous volcanic rock of the walls, creating countless waterfalls.{{cite web|url=http://www.crystalcanyons.net/Pages/TripReports/ReportImages/TrouDeFer/T11.htm|title=Waterfall in the "Corridor"|publisher=crystalcanyons.net|last=Hart|first=John|date=October 2002|accessdate=2009-07-13}}

The team of Pascale Lapoule, Laurent Broisin and Pascal Colas were the first to climb/walk the canyon on 19–21 September 1989.