Ten Fathom Dropoff takes its name from the depth of the wall top – about 19 m, or ten fathoms – from which the reef drops dramatically to 34 m. Deep 6 Diving describes the edge of the wall as decorated by a wide variety of sponges and fixed growth, with the face zig-zagging in a series of overhangs, swim-throughs and cutbacks that give the dive plenty of structure. Nearby, a large boulder sits at 40 m and rises about 12 m, covered in sponges and gorgonian sea fans.

Visibility is usually 30 m or more, which makes the wall feel enormous and gives photographers a chance to capture its scale. Kingfish patrol off the wall, Port Jackson sharks and wobbegongs rest on ledges, and the sponges and fans provide habitat for nudibranchs, sea stars and small fish. On clear winter days the combination of blue water and colourful growth is a highlight of Jervis Bay diving.

This is a dive for experienced deep divers. Depths of 25–34 m on the face, 40 m at the boulder, the exposed position at the bay entrance and occasional current all demand good buoyancy, air management and a planned ascent. Nitrox is useful for the shallower part of the profile. It pairs well with a shallower second dive inside the bay such as The Docks or Longnose Point.

Charters depart Huskisson (Dive Jervis Bay; boats in Currambene Creek). Private boats launch at Huskisson, Callala Bay or Murrays Beach (Booderee), or at Currarong's ocean ramp. From Huskisson cross the bay to the entrance and head for the Point Perpendicular side of the entrance; Operators use their own marks; the site is about 20–25 minutes from Huskisson.

The wall top is at about 19 m (ten fathoms, hence the name).

The outer Beecroft Peninsula cliffs face east to south-east and take the full force of any south-easterly or easterly swell; the sites are diveable in swell under about 1.5 m and are well sheltered from south-westerly and westerly winds, which make them the go-to sites in winter. North-easterly winds (common on summer afternoons) make the run from Huskisson across the bay entrance rough and cause surge on the northern-facing cliffs. Visibility is commonly 15–25 m and can reach 30 m in winter when clear oceanic water sits against the peninsula.

Currents along the cliffs are usually mild but can run at the bay entrance on a strong tide change. Defence live-firing closures can shut the sea area – check before going. Current at the bay entrance can be significant on strong tides.

Descend to the wall top at 19 m and drop down the face, following its zig-zag line through overhangs, swim-throughs and cutbacks at 25–34 m. Experienced divers can visit the large boulder at 40 m. Ascend back along the wall edge and finish your safety stop on the wall top.

EAN28–30 for the 19–30 m section; the 40 m boulder is beyond recreational nitrox MODs – use air or plan as a technical dive.

Dive Jervis Bay (Huskisson; boats Avalon and Genesis) runs double boat dives most days, and Deep 6 Diving Jervis Bay / other Huskisson operators also visit; site chosen on the day according to swell and wind. Deep 6 Diving lists it as a site for experienced deep divers.