Pig Rock sits on the west coast next to Egeria Point, a long boat ride from Flying Fish Cove and one of the least-dived parts of the island. Extra Divers describe it as famous for its towering gorgonian fans and dramatic reef structures with deep drop-offs, and single it out as a site for underwater photographers.

The topography is rugged: buttresses, ridges and heads of reef rise from the slope, with gullies between them, before the edge falls away steeply. The gorgonians are the headline – big, fan-shaped sea fans growing out from the drop-off into the current, their size a reflection of the nutrient-rich water that sweeps along the exposed west coast. Around them the reef is covered in hard corals, sponges and whips, and the fish life includes large tropical species: groupers, snapper, sweetlips, trevally, Napoleon (Maori) wrasse and schools of fusiliers and surgeonfish. Reef sharks patrol the drop-off, and the proximity of Egeria Point – rated one of the island's best shark dives – means grey reef and silvertip sharks are possible.

Graded intermediate to advanced by Extra Divers, Pig Rock needs calm seas for the long run south and good buoyancy around the fragile fans. Currents on the west coast can be stronger and less predictable than on the north. The water here is often exceptionally clear, making it ideal for wide-angle photography of fans against the blue.

It suits experienced divers and photographers, and is usually paired with Egeria Point on the same trip. Few groups reach it in a season, so the reef shows almost no sign of diver damage.

Fly from Perth (about 4 hours, two to three flights a week, some via Cocos Islands) and hire a car – there is no public transport. Both dive centres are in The Settlement and launch their boats from the jetty/boat ramp at Flying Fish Cove, normally at about 8 am for a two-dive morning trip. From the cove the boat runs west along the north coast and then south down the west coast along the coast for roughly about 50–55 minutes to Pig Rock.

There is no land access to the dive, and the vertical sea cliffs mean no exit other than the boat. Operators choose sites on the morning according to swell and wind.

On the exposed west coast, a long run from Flying Fish Cove, so it is only dived on calm days. The site is sheltered from the south-east trades (roughly May–November) but wide open to north-westerly monsoon swell (December–April) and to long-period south-west groundswell generated in the Southern Ocean, which wraps around Egeria Point. Operators generally need less than about 1–1.5 m of swell and light winds to make the trip; the calmest spell is usually August–November.

The west coast has a reputation for stronger and less predictable currents than the north, and for the clearest water on the island (often 40 m+). Visibility can drop during red crab spawning (Oct–Jan). Cyclone season is November–April.

Descend onto the reef structure at about 12 m, head to the drop-off where the big gorgonians are at 18–22 m, and work along with the current. Ascend over the reef structures for the second half and deploy a DSMB for the safety stop.

Extra Divers Christmas Island – dives Pig Rock and neighbouring Egeria Point on calm west-coast days; CI Wet'n'Dry Adventures – occasional.