Aliwal Shoal

The day starts on the beach at Umkomaas, where the boat is pushed into the shallows and timed out between sets, a wet and committing launch that most people remember longer than the short run out to the reef. Dives are run live: you are dropped, the skipper follows your bubbles and collects you wherever you surface, so nothing is anchored and nobody swims back to a shotline. Two dives is the standard morning, either side of a surface interval or a second launch.

The reef lies about 5 km out, a long ridge of cemented dune sand set parallel to the coast and split into an inshore and an outer edge. Gullies, overhangs and short swim-throughs cut through it where the rock has been undercut, and the outer margin drops away into sand. The Agulhas runs down the coast from the north, so which edge you dive, and which way you drift along it, is settled by the current on the day rather than by request.

Winter is when the ragged-tooth sharks stack up, and for many divers they are the reason for the trip: heavy, slow, snaggle-toothed animals that hold station under the overhangs and let a settled diver watch from a few metres without reacting. They are the same species sold as sand tigers elsewhere, and they hover by gulping air at the surface to trim their buoyancy; the winter gathering is generally read as part of their breeding cycle rather than feeding.

Some operators separately run baited dives in open water off the reef, where a bait drum draws sharks in and the group stays tight around it. That is a different exercise with a different rhythm, and it is worth deciding which one you have booked. The two wrecks sit deeper, near 30 m, and are run as their own dives rather than tacked onto a reef morning. Otherwise conditions decide: the Mkomazi River mouth is beside the launch, so a wet week inland can turn the inshore water opaque while the outer reef stays clear.