Hopkins Reef lies directly off the mouth of the Hopkins River at the eastern end of Warrnambool's Lady Bay, opposite Logans Beach where southern right whales calve each winter. It is an exposed limestone reef in 6–12 m shaped like a horseshoe, with a high wall on its outer side and multiple ledges and gutters cut into it, and it is the best natural reef dive in Lady Bay for a small boat. The wall and ledges carry the dense growth typical of the Warrnambool coast – kelp on the tops, sponges, ascidians and bryozoans on the faces – and the gutters are full of life. The Scuba Doctor lists Port Jackson sharks, large wobbegongs and stingrays as the regulars, along with the standard western Victorian fish community of blue-throat wrasse, magpie perch, sea sweep, herring cale, zebrafish and leatherjackets, and southern rock lobster in the deeper ledges. Divers describe the scenery as exceptional for the depth.

It is an easy dive in depth and navigation – follow the wall around the horseshoe and you come back to where you started – and suitable for Open Water divers with a boat, but it is not a sheltered one. The reef takes the full south-west swell and the bottom surges in anything over a metre, and the river mouth beside it turns the water brown after rain. Given a flat autumn morning with 10–15 m visibility it is a genuinely good dive twenty minutes from the ramp, and it pairs with the Edinburgh Castle wreck 1.2 km to the north-west for a two-dive day in the bay. From June to September the whale-watching regulations apply to boats approaching the site, and the presence of a right whale and calf a few hundred metres away is not an unusual bonus.

Launch at the Warrnambool (Lady Bay) boat ramp beside the breakwater at the end of Viaduct Road and run east across Lady Bay for about 3 km, 10–15 minutes, to the reef off the Hopkins River mouth, opposite Logans Beach and the whale-watching platform. Anchor on sand beside the reef rather than on it. The ramp is sheltered by the breakwater but the bay entrance can be rough in a southerly swell.

Warrnambool Diving on Fairy Street supplies air and can advise on conditions.

The Scuba Doctor's rule is that calm conditions and a very flat sea are needed to dive in this area. Hopkins Reef is fully exposed to the south-west swell that rolls into Lady Bay, and at 6–12 m the surge is felt on the bottom in anything over about 1 m. Aim for swell under 1 m with light north to north-east winds; southerlies and westerlies make the bay entrance and the site unworkable.

The Hopkins River discolours the water for days after rain, and the reef sits right off the mouth, so avoid the week after a flood. Mornings before the sea breeze are best. Southern right whales calve off Logans Beach in June–September and must be given 200 m by boats.

Anchor on sand outside the horseshoe, descend to 10–12 m and follow the high wall around the inside of the horseshoe, checking the ledges and gutters for Port Jackson sharks, wobbegongs and crays. Complete the circuit back to the anchor, turn at half gas if you have not, and ascend the anchor line with a 3-minute stop.

Warrnambool Diving (Fairy Street) – air fills, guided dives and occasional boat trips; local club divers with private boats. No scheduled charter.