Sugarloaf Rock is one of the landmark granite rocks of the Cape Naturaliste coast, famous with photographers and known for its seabirds. Underwater it is a site for experienced divers on rare calm days. Marinelife.org.au describes a weedy reef in the shallows with small fish, depths of 17-22 m further out, difficult entry and exit over rocks and gravel, and boat access to the deeper reefs; it stresses that the site is very exposed to swell. The Margaret River region's ocean-safety guide lists it as 'pretty accessible', which holds true only in flat conditions.

The granite here meets the full force of the Indian Ocean, so the reef is shaped by swell: kelp and weed in the shallows, boulders and gutters, and deeper reef with sponges and fish. Western blue groper, buffalo bream, wrasse and herring cale are typical of this coast.

It suits experienced shore divers and freedivers who can judge swell and handle a rocky entry, or boat divers on a calm day. It is not a beginner site. Always watch the sea for several sets before entering and have a clear exit plan.

Sugarloaf Rock lies within Leeuwin-Naturaliste National Park on land and the Ngari Capes Marine Park at sea; check zoning before fishing or collecting.

The coast from Cape Naturaliste south is the Indian Ocean side of the Capes, where the sheltered conditions of Geographe Bay give way to open-ocean swell. Sites here and offshore demand far more attention to forecasts than the bay sites: long-period south-westerly groundswell can arrive on an otherwise calm, sunny day, and conditions can change within an hour.

From Dunsborough drive about 15 km toward Cape Naturaliste and take Sugarloaf Road to the Sugarloaf Rock car park in Leeuwin-Naturaliste National Park. A short path leads to the lookout; the shore entry is over rocks and gravel and difficult. Boat access to the deeper reefs is possible from a nearby ramp (marinelife.org.au) in calm weather.

The nearest full-service dive shop for fills and hire is Swan Dive in Busselton; there is no dedicated dive shop in Margaret River or Augusta, so bring filled cylinders.

On the Indian Ocean side of the cape and very exposed to swell (marinelife.org.au). Only on rare flat days with easterly winds, usually in summer or autumn; any south-westerly swell makes the entry dangerous. The Margaret River region guide describes it as pretty accessible on the right day.

General pattern in Geographe Bay: sheltered from south-westerly swell by Cape Naturaliste; summer mornings are calm before the afternoon sea breeze, while winter north-westerly fronts roll swell and chop into the bay and reduce visibility for several days.

Enter carefully over the rocks in flat conditions, explore the weedy shallows and work down to the deeper reef only if conditions are benign; exit where you entered, timing the sets. Agree a turn pressure before descending (half gas, or a third where current is likely), carry a DSMB, and make a 3-minute safety stop at 5 m.

No regular operator; experienced local divers and freedivers only. Nearest dive services: Swan Dive (Busselton/Port Geographe) for fills, hire, nitrox and charters; no dive shop in Margaret River or Augusta.