The chasm
A hole in the forest where several waterfalls drop together into a chasm nobody can walk to. A Trou de Fer helicopter flight is the only practical way to see it, and it is the single sight on this island that most convinces people the flight was worth the money.
Quick answer
Trou de Fer is reached from the air and no other way. It sits in the Belouve forest above the Cirque de Salazie, where the Bras de Caverne and several other streams fall together into a chasm around 300 metres deep. There is a forest walk to a lookout above the rim, and it shows you the top of the drop and not the hole. Every Trou de Fer helicopter flight is one of the longer circuits, from $422.
What it actually is
Rainforest that ends in a 300-metre hole, with no way to stand at the bottom.
The Belouve plateau is rainforest — tree ferns, moss, permanent damp — sitting on top of the wall above Salazie. Water collects across it and then the ground simply stops. The Bras de Caverne and its neighbours go over the edge together into a chasm roughly three hundred metres deep and barely wider than it is tall.
Because the walls overhang and the floor is a river bed choked with fallen rock, there is no path down and no realistic way to stand at the bottom. The walk out through the Belouve forest reaches a lookout on the rim, and what it gives you is the lip of the falls and a lot of cloud. The chasm itself, with several falls landing in it at once, only assembles into one picture from above.
This is why a Trou de Fer helicopter flight tends to be the moment people describe afterwards. Everything else on the island has a road, a viewpoint or a trail attached to it. This does not.
Trou de Fer sits on the wet, eastern side of the island, which clouds over earlier than anywhere else. If it is the thing you most want to see, take the first slot of the day and book early in your trip.
Cloud and cancellations→Book direct
Every Trou de Fer helicopter flight is one of the longer circuits, which cross the island and come back down the other coast. The forty-five-minute route reaches the cirques and the volcano; the chasm itself is on the fifty-five-minute circuits.
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What else is on the same leg
The east side of the island is compact, and the chasm sits in the middle of the best of it.
The greenest of the three cirques, directly below the Belouve wall, and the only one with a road running up its floor.
The bridal-veil falls on the Salazie road, a long thin cascade down a rampart, visible from the air in the same minute as the cirque.
Tree ferns and moss on the plateau above, one of the wettest places on an island that is already very wet.
Further east, a hydroelectric valley with waterfalls on both walls and no road along its length.
Getting the picture
Summer for water, winter for clarity, the first slot always, and a fifty-five-minute route.
Season. The falls are at their strongest in the austral summer, December to March, which is also the cloudiest and wettest time of year. The dry season, May to October, gives clearer air and thinner falls. If the chasm is the priority, late March and April are the compromise: the water is still up and the mornings are steadying.
Hour. First slot, without exception. The eastern side is the wet side, and it builds cloud earlier than the cirques do.
Route. Only the longer circuits reach it, so a Trou de Fer helicopter flight means a fifty-five-minute listing. The crossings at $422 are the ones to book, and they carry the most reviews of anything on the island.
Expectation. On a marginal day the pilot will fly the route and the chasm may be under cloud while the volcano is clear. That is not a failed flight; it is the east side of Reunion behaving normally.
The rest of the east
Salazie, Takamaka and the lava coast, all on the same leg.
A Trou de Fer helicopter flight is never only about the chasm, because the chasm takes about ninety seconds and the route to it is some of the best ground on the island.
The eastern side of Reunion is the wet side. Trade winds arrive here first and drop most of their water on this coast, which is why the Cirque de Salazie below the Belouve wall is green in a way the southern cirques are not. A Trou de Fer helicopter flight usually runs the length of that wall, and after heavy rain the ramparts carry dozens of unnamed falls at once.
South of it the Takamaka valley cuts back into the highlands, with hydroelectric intakes on its floor and waterfalls down both sides. There is no road along it. Further south again the Grand Brule carries the black lava of Piton de la Fournaise down to the sea, and on the fifty-five-minute circuits a Trou de Fer helicopter flight takes that in on the same leg.
Which is the argument for the longer route. The chasm is the headline; the east coast is what fills the other twenty minutes.
Common questions
You can walk to a lookout on the rim through the Belouve forest, which shows you the top of the falls. There is no path into the chasm itself, so a Trou de Fer helicopter flight is the only way to see the hole with the falls landing in it.
A Trou de Fer helicopter flight means one of the fifty-five-minute island circuits, from $422. Shorter routes stay on the volcano side or in the cirques.
Around three hundred metres, with several streams converging over the lip into the same chasm.
In the austral summer, December to March, which is also the wettest and cloudiest season. April is the usual compromise.
No Trou de Fer helicopter flight can promise it. The eastern side of the island clouds over earliest, which is why the first slot of the morning matters more here than anywhere else.
If the chasm is the image that made you want to fly, yes — nothing shorter reaches it, and the fifty-five-minute circuits are also the lowest cost per minute of any helicopter here.
Go deeper
From $196 to $422, and what a minute in the air is worth.
The verdictOne recommendation for each town, and why.
No roadFourteen kilometres by seven, and not one road into it.
The volcanoTwo thousand six hundred metres of active crater.
The cirquesMafate, Cilaos and Salazie in thirty-six minutes.
The townsFour towns, and what each one puts under you first.
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