Anser Island is the middle island of the Anser Group, the cluster of steep granite islands that Parks Victoria's park note lists among the Prom's popular locations for experienced divers alongside the Glennie Group, South East Point, Waterloo Bay, Bare Back Cove and Horn Point. The island is a dome of pink granite with sheer faces on its exposed southern and western sides and a more broken boulder slope in the lee, and its underwater profile follows the same pattern: near-vertical walls dropping to 30–40 m on the seaward side, and a slope of house-sized boulders with gutters, overhangs and swim-throughs on the sheltered side, all under a fringe of bull kelp. The growth is the exposed-Prom sponge garden – colourful sponges, yellow zoanthids, gorgonians, sea whips and bryozoans – with crayfish in the ledges and blue devils and bullseyes in the shaded gaps; fish schools of butterfly perch and sweep hang off the walls, and the fur seals that breed on Kanowna and haul out across the group are frequent company.

Visibility is typically 15–30 m. Between Anser and Cleft Island lies Carpentaria Rock, where the iron steamer Gulf of Carpentaria struck and sank in 1885; the wreck at 45–50 m is a technical dive covered separately. Anser Island is dived rarely – it shares the weather, distance and boat requirements of the whole southern group – and is usually a second dive after Kanowna or Skull Rock when the boat is already out there.

It rewards divers who want the group's granite scenery and sponge cover without the seal-colony exclusion zones or the 55 m walls, and it is a sensible choice for the boat's less experienced divers while others do the deep sites.

Boat only. The nearest launch is the Tidal River beach ramp at the western end of Norman Bay (4WD beach launch, key and deposit from the Parks Victoria office; needs several people and calm surf), from which the western islands are 5–12 km. Larger trailer boats launch at Port Welshpool (sealed ramp, Corner Inlet) and run about 50–60 km around South East Point – 1.5–2 hours – or at Sandy Point (Waratah Bay, beach ramp) and run 35–45 km south-east.

Sites are exposed to Bass Strait and require settled weather, a seaworthy boat, radio, and self-sufficiency: there is no rescue or refuelling closer than Port Welshpool. Anser Island lies about 12 km from Tidal River between Kanowna and Skull Rock, so it is usually dived on the same day as one of them; anchor on the lee side in sand or keep the boat live. The Gulf of Carpentaria wreck (1885) lies on Carpentaria Rock between Anser and Cleft Islands and is a separate technical dive.

Open Bass Strait with shelter only in the immediate lee of the island; needs calm seas, swell under 1 m and light winds, and slack water for the deeper walls, as current runs between the Anser Islands. Late summer and autumn most reliable. White sharks frequent the group because of the seal colonies.

Descend the anchor line on the lee side to the boulder slope at 15–20 m, work along the island with the rock on one shoulder, dropping to a planned maximum on the steeper faces, then return at a shallower level through the kelp gullies where seals visit. Ascend the line or under an SMB with a full safety stop.

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.