Egg Rock is the Keppels' flagship advanced dive and the site local instructors talk about when they want to sell the area. The rock itself is a modest granite islet, but underwater its seaward face falls away in steep walls, ledges and cracked boulders to about 30 m, with a field of bommies on the sand at around 20 m. Because it sits inside a Marine National Park (Green) Zone and has been protected from fishing for decades, the fish are noticeably bigger and less wary than elsewhere in Keppel Bay: large coral trout, estuary cod, sweetlips and red emperor hang around the bommies, barramundi cod and hussar shelter under ledges, and schools of hump-headed batfish drift off the wall.

The rock is known for its crevices and short swim-throughs, many lined with soft corals, sponges and small gorgonians. Olive sea snakes are regular and inquisitive, bull rays rest on the sand at the base of the wall, and turtles feed along the shallower edges. Clownfish anemones grow down to about 10 m, making a colourful end to the dive.

This is inshore Great Barrier Reef, so do not expect Coral Sea visibility; 10-15 m is typical and 20 m is a good day in winter. What Egg Rock offers instead is structure, fish biomass and the feeling of a genuinely wild site within a short run of a resort island. It is the site that shows how well the Keppels' green zones work, and it is a good contrast with the shallower fringing reefs around Great Keppel that most visitors snorkel.

Egg Rock suits divers with Advanced certification and some current experience, comfortable with drift entries and descending without a fixed line. Newer divers are better served by Man & Wife Rocks or Big Peninsula and can build up to Egg Rock later in a trip if the weather holds.

Drive 40 km (about 40 minutes) from Rockhampton to Yeppoon, then 7 km south along the Scenic Highway to Keppel Bay Marina at Rosslyn Bay Harbour, where there is free and paid parking. Freedom Fast Cats and Keppel Konnections ferries run to Great Keppel Island (Fisherman's Beach) in about 30 minutes; Keppel Dive & Water Sports picks up certified divers from the island. Egg Rock is roughly 15-20 minutes by dive boat from the Keppel Dive hut on the Spit, or about 45 minutes by private boat from Rosslyn Bay; there is no public mooring, so boats drift-drop or anchor carefully on sand clear of coral.

It is only visited when wind and swell are low.

Keppel Bay is exposed to the prevailing south-east trades (strongest April-September) and to summer northerlies. Egg Rock is the most exposed of the regular Keppel sites and needs light winds (under about 10-12 knots) and minimal swell; any sustained south-easterly or a northerly over 15 knots rules it out. Currents run hard around the rock on spring tides, so dives are planned near slack or on neap tides.

Visibility is best July-October (15 m+) and drops for several days after strong winds or heavy rain, when Fitzroy River run-off discolours Keppel Bay. Summer storms and cyclones (November-April) can close the site for extended periods.

Descend on the sheltered side of the rock and follow the wall down its seaward face to 20-25 m, working through the crevices and swim-throughs with the current on your shoulder. After 15-20 minutes turn back up-current along a shallower contour (10-15 m), visit the anemone patches above 10 m, and complete the safety stop in the lee of the rock where the boat can pick you up.

Keppel Dive & Water Sports (PADI 5 Star, based on the Spit at Great Keppel Island next to Great Keppel Island Hideaway) runs guided boat dives to the Keppel sites most days, weather permitting, plus courses and Discover Scuba; site choice is made on the day according to wind. Private boats from Rosslyn Bay also dive here. Egg Rock is the operator's favourite advanced site but is only scheduled on calm days.