Leopard Seal Reef lies on the southern, exposed side of Lady Julia Percy Island between Thunder Point and the island's south-western cliffs. From the boat it shows as a visible triangular reef coming out from the cliff, with an above-water cave immediately to the north, and the position was recorded by Peter Ronald, the Warrnambool diver and maritime archaeologist responsible for many of the west coast's verified wreck and reef marks. The site's most distinctive feature, in the Scuba Doctor's words, is a set of giant underwater rock pools in 10–14 m, complete with oversize pebbles to suit: basins scoured into the basalt by the swell and floored with rounded boulders the size of cars, separated by walls and ridges that continue seaward to about 20 m. It is a landscape rather than a wall, and in clear autumn water it is one of the most photogenic pieces of bottom around the island. The reef carries the island's usual heavy cold-water growth – sponges, ascidians, bryozoans – with crayfish in the crevices, schools of sweep and butterfly perch over the ridges, and the fur seals that are never far away at Deen Maar. The name records the leopard seals that haul out on the island in some winters, vagrants from the Antarctic pack ice.

Because it is on the southern side, the reef is only diveable in northerly weather when the island shelters it from wind and the south-west swell is small; in the more common southerly conditions Landing Bay on the northern side is the alternative. It is an Open Water depth dive but rated Advanced for the remoteness, the exposure and the seal and shark considerations that apply to the whole island. Landing is prohibited without a permit, the island being a Wildlife Reserve within the Deen Maar Indigenous Protected Area, and great white sharks frequent the colony. For a party already at the island, Leopard Seal Reef and the Blowhole next door are the southern-side dives to aim for.

Boat only, from Port Fairy (Griffiths Street ramp, about 20 km) or the Yambuk river ramp to the southern side of the island. The reef is visible as a triangle coming out from the cliff with an above-water cave immediately to its north; the Blowhole at Thunder Point is 384 m to the south-west. Anchor on sand off the reef in northerly weather when the southern side is in the lee.

Landing is prohibited.

Lady Julia Percy Island stands 8 km offshore in the open Southern Ocean and the crossing from Port Fairy or Yambuk is exposed in any weather; the island offers a lee on one side or the other but nowhere is calm in a swell over about 1.5 m. Plan for a south-west swell under 1–1.5 m and winds under 15 knots, choosing sites on the northern (Landing Bay) side in southerly weather and the southern side in northerlies. The Bonney Upwelling brings cold, nutrient-rich water from November to April, when visibility can drop and water temperatures fall to 13–14 °C even in summer; autumn generally gives the clearest water.

Great white sharks frequent the colony, particularly during the pupping season from November to January. Diveable perhaps 30–40 days a year for a boat based in Port Fairy. The southern side is only workable in northerly winds with a small south-west swell; in southerly weather use Landing Bay on the north side instead.

Anchor on sand off the triangular reef, descend and swim in to the giant rock pools in 10–14 m, exploring the boulder-floored basins and the walls between them, then follow the reef out to its deeper end at 18–20 m. Turn at half gas, return along the reef to the anchor and complete a 3-minute stop, watching for seals and, in winter, the leopard seals that give the site its name.

No regular charter. Port Fairy and Portland fishing charters take divers to the island by arrangement in settled weather; Warrnambool Diving and Melbourne clubs organise occasional trips; most dives are from private boats out of Port Fairy or the Yambuk (Eumeralla River) ramp.