The Bluff at Barwon Heads is the headland that closes the mouth of the Barwon River, a ridge of basalt and older sandstone that pushes out into Bass Strait as Point Flinders and shelters the river town behind it. Its waters were declared the Barwon Bluff Marine Sanctuary in 2002, 17 hectares of reef and sea life that Parks Victoria describes in terms of kelp forests, sandstone arches and colourful sponge gardens, and it is the Bellarine's principal ocean shore dive. The geology splits the site in two.

The eastern half, facing the river, is basalt reef washed by river flow and gives the calmer, shallower dive; the western half, facing the ocean, is old sandstone eroded into ledges, gutters, overhangs and small arches and carries the richest life. Between the reef pincers at the tip of Point Flinders is a small bay with a floor of sand and rock. Kelp forests of crayweed, bull kelp and giant kelp cover the outer reef, and beneath them are sponge gardens, feather stars, sea tulips, barnacles, mussels and sea slugs in numbers.

Fish are those of the open Victorian coast rather than the bay: Western blue groper, horseshoe and six-spined leatherjackets, magpie perch, boarfish, herring cale, zebrafish, Port Jackson sharks, smooth stingrays and, on the sand, large rays. The wreck of the SS Orungal (1940) lies about 700 m off the northern side and the Earl of Charlemont (1853) is buried off the southern side; both are documented separately. The dive is a step up from the bay piers: a rock-shelf entry, Bass Strait surge, kelp and a real requirement to read the swell, and The Scuba Doctor notes that it is better with little or no swell but that for the experienced the swell adds to the challenge and beauty.

Rockfalls from the cliffs are a documented hazard on land, and high tides cut the beach off below them. The Bluff is also the staging town for the ex-HMAS Canberra, 3 km east, and the two make a natural weekend.

Barwon Heads is 20 km south-east of Geelong via the Barwon Heads Road (25 minutes) or 100 km from Melbourne. Drive through the village and up Bluff Road to the two car parks on the headland; the first suits dives on the southern (ocean) side and the second, larger one suits the northern (river) side. Stairs lead down to the beach at beach markers 27W and 28W, a carry of 150-250 m including the steps.

Walk onto the rock shelf and enter from its edge where the swell allows. Before gearing up, walk over the crest of the Bluff and look at the sea. Exit at the same shelf.

The two sides are documented in detail as Barwon Bluff North and Barwon Bluff South.

A Bass Strait shore dive: diveable only with little or no swell (under about 1 m at the Bluff) and light winds, ideally northerly to north-easterly; any south-westerly swell or southerly wind breaks over the rock shelf and makes the entry dangerous and the water surgy and murky. Autumn and early winter give the most flat days. Avoid the eastern (river) side after rain, when the Barwon River discharges brown water and visibility collapses; the western side clears sooner.

Check the sea from the lookout on the Bluff before gearing up; if there is white water on the shelf, do not dive. Dive around high tide for depth over the shelf, but be aware that high tides cut off the beach below the cliffs.

Choose the side by the swell and the river: in clean water with a small swell enter from the shelf on the southern side, swim toward Point Flinders and the kelp beds at 4-8 m, work the sandstone ledges and arches, turn at half gas and return along the shelf; in a north-westerly or with river colour, use the northern side and the small sandy bay between the reef pincers instead. Ascend in the lee of the shelf.

No regular commercial operator – dived independently and by Geelong and Melbourne clubs; Bay City Scuba (Geelong) and Dive Victoria Group (Queenscliff) are the nearest shops. Parks Victoria licensed operators and the Barwon Coast volunteers run summer rock-pool rambles and snorkels.