Hump Wall is part of a very large section of reef that extends seaward from the Bass Point peninsula, among the deep reefs known collectively as the Humps. At the mark the reef forms a corner, running south and north-west; to the north-east it slopes at about 30° over a boulder-strewn face, while to the south it drops as a sheer wall. The reef top is at 23–24 m, shallowing a little westward before dropping to 27 m and sloping below 30 m, and the base of the wall on the eastern side reaches about 34 m.

The wall is covered in sponges, sea squirts and small gorgonians, and the flat reef top is pocked with small holes and gutters. Black reef leatherjackets, striped seapike, moray eels, large cuttlefish, yellowtail and one-spot pullers are regulars, Port Jackson sharks rest on the reef in season, and McFadyen describes days with thousands of mado and carpets of tiny white feather stars about 15 mm across. Visibility can reach 20 m.

This is only a dive for the very experienced. On air, no-deco time at the wall is about 15 minutes; 32% nitrox roughly doubles that. The combination of depth, limited time and an open-water ascent calls for careful gas planning, a DSMB and good buoyancy. For divers who meet that bar it is one of the most impressive deep walls within easy reach of Sydney, and it complements the smaller, more compact Hump One nearby. Plan the ascent up the anchor line or with a DSMB, as the site is well offshore of the point and boat traffic passes through.

Launch from the Shellharbour Marina boat ramp (Shellharbour Village; trailer parking and toilets), about 105 km and 1.5 hours south of central Sydney. Head east out of the harbour and around Bass Point; run almost due east about 3.5 km to 34° 35.140' S 150° 54.665' E. The reef top is at 23–24 m; anchor on the corner where the reef runs south and north-west.

Bass Point juts well out to sea south of Shellharbour, so its outer reefs take swell from the north-east through to the south. Boat dives here want a swell under about 1.5 m and moderate winds; in a south-easterly the outer sites become rough very quickly, and the short run from Shellharbour Marina means operators can come back in if conditions build. Westerly winds in late autumn and winter give the best flat seas and clearest water, often 15–20 m.

Visibility drops after big seas stir the sand and after heavy rain.

Descend to the corner at 23–24 m and drop down the sheer wall south of the mark to 30–34 m, following it along its sponge-covered face. On air limit the deep section to about 15 minutes (about 30 minutes on EAN32), then return up the 30° slope to the north-east and finish on the reef top.

EAN32 extends no-deco time to about 30 minutes at wall depths; carry a DSMB.

Occasional private and club boats and experienced groups; not a regular charter site.