Big Brother South Plateau

You drop in near the southern tip of Big Brother and move out onto the plateau as the ground falls away. It begins around 30 m and runs some 500 m south, about 20 m wide, with the reef dropping to over 80 m off either side. The first feature is a promontory carrying three or four low hills at around 35 m, a good place to hold station and watch the blue when the visibility is with you. Everything on top is already deep, so the dive is planned around the shallow end of the site rather than the point.

Head south along the ridge and it sinks steadily, reaching 60 m where the plateau ends at the point. This is the corner divers come for. Grey and whitetip reef sharks, hammerheads and oceanic whitetips are all commonly spotted around Big Brother's south-east point, and on a dawn dive in autumn or winter thresher sharks are a possibility here that divers rarely get elsewhere. At 35 m your no-decompression time runs out quickly, and on nitrox it is the depth limit that bites first.

The current usually flows from the north, so the run south is easy and the return leg is the work, and it can change through the dive rather than holding steady. Turn early with gas and time in hand, then make the ascent on the fringing reef, which plunges steeply on all sides and carries dense anthias, glassfish and sweepers over the shallower coral. Carry an SMB: the liveaboard is the only pick-up out here.