GRSE Waterfall Mauritius

The Grande Riviere Sud-Est, or GRSE, is the longest river in Mauritius. Where it empties into the Indian Ocean on the east coast, it creates one of the island's most dramatic natural sights: the GRSE waterfall. The water drops through tropical vegetation, surrounded by cliffs, wild monkeys, and giant fruit bats. And because there are no roads to the river mouth, the only way to experience it is by boat.

Geology and history of the GRSE waterfall

The GRSE stretches roughly 25 kilometres from the central highlands to the east coast. Over thousands of years, volcanic basalt and coral limestone have shaped a narrow gorge near the river mouth. When the river is high, water plunges over a natural basalt ledge into a shallow basin before mixing with the turquoise lagoon. During the dry season, the flow softens into a curtain of mist that drifts across the anchored boats. Dutch sailors first noted the falls in the 17th century, and the name Grand River South East appeared on French colonial maps by 1720. Unlike the man-made cascades at Chamarel, the GRSE waterfall is entirely natural, making it one of the few wild waterfalls you can reach in Mauritius.

Why the GRSE waterfall is only reachable by boat

The waterfall sits inside a wild coastal strip between the river and the sea. There are no hiking trails, viewing platforms, or roads nearby. The local landscape is dense tropical forest and mangrove, which is why every legitimate GRSE waterfall experience is part of an east-coast boat tour from Trou d'Eau Douce.

Wildlife you can spot at the waterfall

The river mouth is a sanctuary for species that have vanished from more developed parts of the island. Keep your camera ready for:

• Crab-eating macaques: small grey-brown monkeys that forage along the riverbank. They are shy but curious, often peering down from overhanging branches.
• Mauritius flying fox: the island's largest bat, with a wingspan up to 80 centimetres. They roost in the tall trees near the falls and are easiest to spot at dawn and dusk.
• White-tailed tropicbirds: elegant white seabirds with long tail streamers that nest on the coastal cliffs.
• Reef fish at the river mouth: where fresh water meets salt water, you will see damselfish, parrotfish, and the occasional small ray.
• Mangrove crabs: scuttling across the exposed roots at low tide, often coloured vivid red or purple.

What to expect at the waterfall stop

• Your skipper slows the boat and drifts toward the river mouth so you can photograph the falls up close.
• Look into the trees for wild monkeys and giant fruit bats resting in the branches.
• The stop lasts 15-30 minutes depending on currents and other boats.
• Passengers stay on board for safety; the water near the falls is too shallow and rocky to disembark.

Photo tips for the GRSE waterfall

Because you are shooting from a moving boat, photography here is different from land-based waterfalls. Use a fast shutter speed of at least 1/500 second to freeze the spray and avoid motion blur. A polarizing filter cuts reflections off the water surface, revealing the dark volcanic rock underneath. Frame the shot with overhanging vegetation for depth, and try to include the colour contrast between the brown river water and the turquoise lagoon. Morning departures give the best light because the sun rises behind the boat, illuminating the falls evenly. Drones are not permitted in this area because of the nearby wildlife sanctuary, so leave the drone in your hotel.

Best time of year to visit the GRSE waterfall

Mauritius has two distinct seasons. From November to April, the summer monsoon brings heavier rain, and the GRSE waterfall is at its most powerful. The flow is loud, dramatic, and surrounded by lush green vegetation. From May to October, the drier winter months produce a gentler cascade with less mud in the water and clearer skies. Both seasons are worth visiting. If you want the classic thundering waterfall photo, come in January or February. If you prefer calm water for snorkeling afterwards and easier photography, June to September is ideal. Morning tours always beat afternoon departures because the river mouth is calmer before the sea breeze builds.

Combine the waterfall with Ile aux Cerfs

The GRSE waterfall is usually the first highlight of a full-day east-coast tour. After the waterfall, boats continue to snorkeling sites and then to Ile aux Cerfs for beach time and a BBQ lunch. This combination is why the Ile aux Cerfs catamaran cruise and speedboat tour are the most popular day trips in Mauritius.

Protecting the GRSE ecosystem

The river mouth is part of a sensitive coastal ecosystem. Our skippers keep a respectful distance from the falls to avoid disturbing nesting birds and roosting bats. Engines are idled low to reduce noise and fuel in the water. We ask guests not to throw anything overboard and to avoid loud noises that might frighten the macaques. By following these simple rules, the waterfall remains pristine for the next boat and the next generation of visitors.

See the waterfall on a full-day tour

Every east-coast tour we run includes the GRSE waterfall, snorkeling, and free time on Ile aux Cerfs.