Key takeaways
- The Grande Riviere Sud-Est comes down through a gorge and reaches the sea on the east coast.
- It is a well known stop by boat, and the estuary below it is where the sediment comes from.
- A ridge above the bay whose profile is the reason for the name.
- The twenty minute flight reaches the river mouth and the shelf edge; the thirty continues to the mountain.
The river
The Grande Rivière Sud-Est is the largest river in Mauritius, which on an island this size means something more modest than the name suggests and is still by a distance the most substantial watercourse here. It rises in the central uplands, runs east through a valley, and reaches the coast on the eastern shore south of Trou d'Eau Douce.
Near its mouth it drops over a fall into a pool, and that fall is a fixture of east coast boat trips: the standard Ile aux Cerfs excursion runs up the estuary to look at it, and there is usually a boat or two sitting below it. From the water it is a green, enclosed, rather secretive place.
From the air it is something else entirely, because you can see the whole system at once. The valley coming down from the interior, the fall, the widening estuary, and then the point where fresh water and sediment meet the lagoon. That last part is the interesting bit, and it is not visible from any boat.
Why the river matters to the flight
The eastern underwater waterfall is not an unrelated curiosity that happens to be nearby. A river delivering sediment to a coast is one of the things that keeps a shallow shelf supplied with material, and the shelf edge off this stretch of coast is where that material eventually goes over the side.
So the river, the estuary and the illusion are one story rather than three sights. Flying south from Ile aux Cerfs you cross the lagoon, pass the mouth of the Grande Rivière Sud-Est, and then reach the point where the shallow platform ends and the sediment streaks down the slope. Seeing them in that order makes the illusion legible in a way that arriving at it cold does not.
It is also why the twenty minute flight goes as far south as it does. That is the geography the flight is built around.
The river valley meeting the coast, with the ridge beyond
Lion Mountain
Further south again, standing over the bay, is Lion Mountain. It is one of the recognisable summits of the southeast, and the name comes from the profile: from the correct angle the ridge reads as a lion lying down, with a head at one end and a body behind it.
Like most things named after what they resemble, it resolves from one direction and dissolves from every other. Approached from the north it is simply a green ridge with steep sides. From over the bay the shape assembles itself, which is one of the small pleasures of seeing it from an aircraft rather than a car park.
It is climbable, and it is a popular walk on the ground, with a scramble near the top and a view over the bay and the historic coast below. That is a separate day out and a good one. What the flight gives you instead is the context: the ridge in relation to the bay, the reef, the river valley to the north, and the pattern of the coast it sits on.
The coast between them
The stretch of shore linking the river mouth to the bay under Lion Mountain is the part of the east coast that has stayed quiet. North of the river is the resort strip and the boat traffic to Ile aux Cerfs; south of it the coast narrows, the ridges come closer to the water, and the settlements thin out.
From the air that transition is obvious and rather abrupt. The lagoon changes shape, the reef comes in closer in places and further out in others, and the green behind the shore stops being sugar and starts being slope. There are fewer boats, fewer roofs and more river valley.
It is also the part of the coast with the longest history behind it, since the bay to the south is where the island's early European settlement and its shipping were centred rather than the modern capital on the other side. None of that is visible as such from a light aircraft, but the shape of the bay explains at a glance why anyone would have chosen it: it is sheltered, it is deep enough, and the reef opens in the right place.
One story
The river, the estuary and the underwater waterfall are one process at three stages: sediment off the uplands, across the shelf, and over the edge of it.
Seeing them from the air
The two landmarks come at the far end of the flight, which changes the character of the second half. The first part is entirely water: lagoon, sandbanks, island, colour. Then land arrives, and with it height, texture and shadow.
That contrast is the strongest argument for the longest flight. Twenty minutes of extraordinary shallow water is a complete experience, and the eye does adjust to it. Bringing in a river valley and a ridge resets the attention, and it also shows you how the island is put together: uplands in the middle, rivers coming off them, sugar country on the slopes, and a reef holding the sea off the whole eastern edge.
Light works differently on this half of the flight too. Water wants sun overhead to show its colour; a ridge wants sun from the side to show its shape. On a mid-morning flight you get reasonable versions of both, which is another quiet argument for that slot.
