Brown Head Pinnacle is a rock tower standing 100 m off the tip of Brown Head, the headland between Larkin Cove and Bare Back Cove, and it is the eastern Prom's bommie dive. Scuba Doctor lists it at 8–35 m and describes a pinnacle reaching within 8 m of the surface, with weed-covered shallows extending down to 20 m, levelling off at 25 m into a gently sloping boulder field covered in marine life, with butterfly perch in clouds and colourful invertebrate life in the deep sponge garden. The structure gives the dive a natural profile: descend the shot to the kelp-covered summit, circle down through the upper reef where the kelp gives way to coralline turf and the first sponges, and arrive at 25 m in the boulder field, where the granite is coated in the eastern Prom's deep-reef community – orange, yellow and purple sponges, zoanthid mats, gorgonians, sea whips, bryozoan lace and jewel anemones – with crayfish under the boulders.

The perch clouds hang off the up-current face of the pinnacle, joined by sweep, bullseyes and boarfish, and the headland current that makes slack-water timing necessary is also what keeps the filter feeders so dense. Draughtboard sharks and blue devils use the boulder gaps. The pinnacle is a small site that can be circled several times in a dive, and its depth makes it the deep dive of this stretch of coast, paired with Larkin Cove or Bare Back Cove for a shallower second.

Like everything here it is reached only by a long run from Port Welshpool in calm weather, and it is dived a few times a year at most.

Boat only. Launch at Port Welshpool (sealed all-tide ramp, jetty and trailer parking on Corner Inlet, 2.5 hours from Melbourne) and run south through Corner Inlet's marked channels and out past Rabbit Island down the eastern Prom coast – about 30–40 km and 60–90 minutes to Sealers/Refuge Cove, longer to Waterloo Bay and South East Point. The coast is exposed to easterly and southerly swell and has no facilities; carry fuel, radio and all air, and plan around the weather window and Corner Inlet tides.

Brown Head is about 35 km from Port Welshpool; locate the pinnacle on the sounder 100 m off the tip (top at 8 m) and anchor in the sand beyond it or drop a shot on the summit. Dive at slack water because of headland currents.

Best with calm seas, no swell and no wind; light offshore south-westerly winds acceptable, strong onshore westerly to easterly winds not. Best at slack water due to currents around the headland. Autumn.

The eastern Prom coast is reached only after a long boat run from Port Welshpool, so the whole day's forecast must be settled: swell under 1–1.5 m, light winds, and no change due. Easterly and south-easterly swell is the main problem on this coast; a westerly wind flattens it but makes Corner Inlet's entrance choppy on the ebb. Visibility is typically 10–25 m and best in autumn after several calm days.

Descend the shot to the summit at 8 m, spiral down the weed-covered upper pinnacle to 20 m and on into the sponge garden where it levels at 25 m, explore the boulder field to a planned maximum of 30–35 m, then work back up the pinnacle and finish with a safety stop on the shot or under an SMB.

No dive charter operates at Wilsons Promontory. Sites are dived from club and private trailer boats – Dive La Trobe, VSAG, Melbourne University Underwater Club and Dive Victoria Group run occasional camping-and-diving trips – launching at Tidal River (beach launch, permit/key from Parks Victoria), Port Welshpool or Sandy Point. Wilsons Promontory Cruises (Port Welshpool) runs sightseeing cruises to Skull Rock and the islands but no diving.