Eagle Rock is the 20 m volcanic stack capped with limestone that stands off Split Point at Aireys Inlet, directly below the lighthouse, and the 17.9 hectare marine sanctuary named for it protects the base of the point between Castle Rock and Sentinel Rock out to about 300 m offshore. Beside the stack is Table Rock, a black basalt platform levelled by the waves; the whole site is a rare outcrop of volcanic rock on a limestone coast, with 20-30 m bluffs, rock platforms, reefs and sea stacks. Parks Victoria's description is candid: when conditions are calm the sanctuary offers great diving and snorkelling along the edge of the platforms and reef, but conditions are often unsuitable because of the high wave energy of this coastline.

When it is calm, the dive follows the platform edges and reef around the stacks in 1-10 m through bull kelp and crayweed that thrive in the breaking waves, over rock covered in sea tulips and encrusting sponges. Twenty-five fish species are recorded, among them blue-throat wrasse, rosy wrasse, sea sweep, herring cale and scalyfin, with Port Jackson sharks, sparsely-spotted stingarees and rusty catsharks under the ledges and on the sand, banjo sharks, stingrays, southern rock lobster, octopus, decorator crabs and sea stars in the reef, and Australian fur seals hauling out on the outer rocks. Blue-ringed octopus live in the rock pools.

The site is entered from Step Beach below the lighthouse lookouts or from the Painkalac Creek beach to the south-west, both involving cliff paths and platforms, and it is emphatically a calm-weather dive: surging swell, rogue waves, currents and undertows are all documented, and the platforms are slippery and exposed. For divers and snorkellers who catch it right it is one of the most scenic shallow dives in Victoria, with the lighthouse above, the stacks around and seals in the water, and the sanctuary status means the crays and fish are undisturbed. Eagle Nest Reef and Sandy Gully lie to the north-east for the same conditions.

Aireys Inlet is 125 km from Melbourne and 48 km from Geelong on the Great Ocean Road. For the north-eastern entry park at the Split Point lighthouse visitor car park off Federal Street (free) and take the cliff-top track and steps down to Step Beach, a carry of 200-300 m with steps. For the south-western entry park on Inlet Crescent and walk to the beach at the mouth of Painkalac Creek, then along to the rock platforms below the point.

Enter from the sand or the platform edge along the base of Split Point and dive along the edge of the platforms and reef around Eagle Rock and Table Rock. Exit at the same point.

Light north to north-west winds with small to no swell are required. Parks Victoria states that conditions here are often unsuitable because of the high wave energy of this coastline, and The Scuba Doctor warns of strong surging swells, wind, poor visibility, rogue waves, strong currents and undertows. Dive only in safe conditions with low waves.

Spring tides reach 1.7 m and neaps 0.9 m; high tide gives depth over the platforms but also more surge at their edges. Water is about 17.5 °C in summer and 13.5 °C in winter. Autumn and early winter give the most usable days; visibility 5-15 m when clean.

Enter at Step Beach on a flat day, swim along the base of the platforms toward Eagle Rock at 3-6 m, circle the stack and Table Rock through the kelp and gutters at 6-10 m, look under the ledges for crays and sharks, turn at half gas and return along the platform edge to Step Beach, staying clear of the surge zone at the platform lips.

No regular commercial operator – dived independently by experienced Geelong and Surf Coast divers and clubs on the rare flat days; Bay City Scuba (Geelong) is the nearest shop. Snorkel tours operate under Parks Victoria licence in summer.