Dannevig Island is the southern member of the Glennie Group, named for the Norwegian-born fisheries scientist Harald Dannevig, and its north-eastern tip is listed by Scuba Doctor as a 5–30 m wall dive with one outstanding feature: a large cave at about 25 metres down close to the northern tip of the island, with multiple entrances. The site's structure is a steep rocky slope from the kelp line to about 15 m, giving way to massive boulders between 25 and 30 m that create excellent swim-throughs, and the cave is formed where the largest of those blocks lean together. It is a granite boulder cave rather than a solution cave – roomy, with several openings that admit daylight – but it is deep enough and dark enough inside that a torch and conservative penetration are needed.

The walls of the cave and swim-throughs carry the Glennie Group's richest growth: sponges in orange, yellow and purple, zoanthids, bryozoan lace, jewel anemones, gorgonians and sea whips, with bullseyes packed into the roof, blue devils and crayfish in the recesses, and the occasional draughtboard shark or conger eel. Outside, the slope carries perch and sweep schools, boarfish and morwong, and seals from the Glennie haul-outs. Bum Rock, the famous cracked boulder, is 620 m to the south-south-west on the island's western side.

Dannevig North East is one of the most distinctive dives in the Glennie Group and is generally the second dive of a club day after Great Glennie or Ramsbotham Rocks, weather permitting; it is reached from the Tidal River beach launch or on the long run from Port Welshpool, and is dived only a few times a year. It suits Advanced divers comfortable at 25–30 m in boulder overheads.

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. Dannevig is the southern island of the Glennie Group, about 8 km and 25–35 minutes from the Tidal River beach launch; anchor in sand off the north-east tip in 15–20 m or keep the boat live over the deep boulders.

The north-east tip is in the lee of the island from the prevailing south-westerly but open to northerly and easterly winds and to swell refracting around both ends of the island; needs calm seas and swell under 1–1.5 m. Late summer and 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 anchor onto the steep rocky slope and follow it down to 15 m, then on to the massive boulders at 25–30 m near the northern tip, where the cave with multiple entrances opens; explore the entrances and swim-throughs with a torch without penetrating beyond daylight, turn at half gas or NDL, and climb the slope back to the anchor for a safety stop.

No true overhead environment if penetration is kept within sight of an exit; EAN32 useful.

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.