Ile de la Passe

Ile de la Passe is a low islet sitting beside the only navigable pass through the reef into Grand Port bay, which made it the key to the harbour and the reason both the French and the British fortified it. In August 1810 a British force took the island, then used its captured signals to lure a French squadron into the bay, where the ensuing engagement went badly for the British and became the only naval defeat recorded on the Arc de Triomphe. The fort remains: gun emplacements, powder magazines, barrack rooms and a signal station on the rock, weathered but substantial, with the reef breaking a short distance away. Boats run from Mahebourg, and the trip usually combines with snorkelling in the lagoon.

What to look for

• The gun batteries - the emplacements facing the reef pass.
• Powder magazines and barracks - the surviving fort buildings.
• The reef pass - the channel the fort was built to control.
• Grand Port bay - the water where the 1810 engagement was fought.

When to go

May to December for calmer crossings; the pass is exposed and the boat trip is cancelled in rough conditions. Morning departures are usual. Trips need arranging in Mahebourg rather than turning up.

Things to know

Landing depends entirely on sea state and trips cancel often. The fort is unrestored, with loose masonry and no railings. There is no shade and no facilities on the islet. Access is only by chartered or arranged boat.

Nearby

Mahebourg lies west; Blue Bay is in the same lagoon.