Passe St Jacques

Down in the island's quiet southwest, Passe St Jacques is Mauritius's version of a channel drift: when the tide pushes in, divers drop at the seaward mouth and fly over the pass floor with the lagoon pulling them home. The current line carries the traffic — eagle rays holding like kites, schools of trevally and barracuda stacked in the flow, big stingrays on the sand, and gray sharks making occasional appearances at the deeper outside edge. It is dived far less than the west-coast circuit, needs the right tide and a skipper who knows it, and rewards with the island's most exhilarating twenty minutes.

The moment you come for: Fast incoming-tide drift; eagle rays and jack schools riding the pass

Topography: Lagoon pass in the southwest with rubble-and-coral floor sloping to the open sea

Current: A true tidal pass — dived on the incoming flow, and only when the operator judges the window right.

Hazards: Strong tidal current, boat pickups in moving water, and quick depth changes along the pass.

Conservation: Drift with the flow rather than finning against it — contact damage happens when divers fight the pass.

Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).