Trou-aux-Biches tide times

Trou-aux-Biches sits 5 km south of Grand Baie on the sheltered northwest coast of Mauritius, where the barrier reef runs closest to the shore and the lagoon between reef and beach is at its narrowest and shallowest. The beach arc is roughly 1.2 km of fine white sand lined with casuarina trees; a public beach occupies the northern two-thirds and the Trou-aux-Biches Beachcomber Resort — one of Mauritius's longest-established resort properties — fronts the southern section.

The name, which translates loosely as Deer Hole, refers to a freshwater spring that used to emerge near the beach before the area was developed; there is no surface trace of it today. The beach itself is the reason to be here: the lagoon inside the barrier reef is exceptionally calm, the sand is fine enough to squeak underfoot when dry, and the casuarina shade makes midday on the beach bearable.

The tidal regime is semidiurnal, with spring range 0.8–1.0 m above chart datum and neap range 0.3–0.5 m, following the Port Louis reference gauge. The lagoon at Trou-aux-Biches is shallower than Grand Baie — the reef runs only 300–500 m offshore here — and the tidal effect is more visible. At mean water level the lagoon over the sand and seagrass beds between the beach and the reef is 0.5–1.5 m deep; at low spring water the seagrass beds closest to the beach shallow to 0.1–0.3 m and the light-coloured sand shows clearly through the water. At high spring water the same beds are 0.8–1.3 m deep — enough for comfortable snorkelling across the full lagoon width without scraping the seagrass.

The seagrass beds at Trou-aux-Biches are feeding habitat for green sea turtles (Chelonia mydas), which graze the beds at dawn and dusk. The best observation window is the early morning, 06:00–08:00, when turtles are most active before boat traffic begins. The high-water window during those hours provides the clearest view into the grass beds without the sun glare that builds by 09:00. A slow wade or quiet snorkel along the outer margin of the seagrass toward the reef is more productive than swimming directly over the feeding area.

Glass-bottom boat tours to the outer reef operate from the public beach area, with typical departures at 09:30 and 14:00. The excursion follows the lagoon channel to a pass in the outer reef and crosses into open water to show coral formations and fish on the outer reef slope. The outer reef diving and snorkelling is substantially richer in coral cover and fish diversity than the inner lagoon. The best visibility on these tours is during the flood tide or at high slack water; the outgoing tide carries suspended sediment from the lagoon through the reef pass and reduces visibility on the outer reef face.

Shore anglers working the Trou-aux-Biches lagoon at dawn target the species that move onto the seagrass flat on the incoming tide — bonefish (Albula vulpes), bluefin trevally, and barracuda patrol the grass edge in the low-light hours. The last two hours of the incoming tide, when water is still rising over the grass and the predators are actively hunting, is the most productive window. A light spinning rod and a small jig or live bait cast to the seagrass edge is the standard approach.

For families, Trou-aux-Biches is one of the most consistently calm and shallow beaches on Mauritius. The lagoon depth at 30 m from shore at high water is 0.6–1.0 m — waist depth for most adults, knee depth for children — and the absence of surf or significant current makes it safe for young children to wade. The public beach has picnic tables under the casuarinas, a bus stop on the coast road behind the beach (Bus Route 215 from Port Louis), and a selection of small restaurants within 200 m.

Predictions for Trou-aux-Biches on this page come from Open-Meteo Marine, a gridded global ocean model; accuracy is typically ±45 minutes on timing and ±0.2–0.3 m on height.