Outer Rock is the largest of the isolated rocks on the north-eastern edge of Keppel Bay and a scenic trip even above water, with seabirds on the rock and humpback whales passing in winter. Underwater it offers a sheltered bay where boats can anchor, and from there divers explore gutters, boulders and coral gardens down to about 18 m. The rock is well covered with hard and soft corals, ascidians and gorgonians.

Maori wrasse are a feature, along with painted crayfish in the gutters, olive sea snakes, and green and loggerhead turtles. Being further out, the site draws pelagic fish, and divers report rays and reef sharks, with anemonefish and pipefish for those looking closer. The layout makes navigation straightforward: follow the base of the rock one way and return shallower.

Depths are moderate and the bay is protected, so the dive suits Open Water divers who are comfortable with a longer boat ride. Outer Rock is often paired with Man & Wife Rocks, which lie between it and Great Keppel. It is less dramatic than Egg Rock but more consistent, and on a clear winter day, with whales audible underwater, it is one of the most memorable dives in the Keppels.

Outer Rock should not be confused with the other Outer Rock off Bustard Head, south of Gladstone, which is a separate and much more exposed site. In the Keppels it is simply the furthest of the rocks on the north-eastern side of the bay. The island's seabirds nest on the rock, so boats stay well clear of the top and the dive begins in the anchoring bay.

On calm days a second dive is often made at Man & Wife Rocks on the way back to Great Keppel.

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. Outer Rock is about 25-35 minutes by dive boat from Great Keppel, or roughly 50 minutes by private boat from Rosslyn Bay.

Boats anchor in the rock's sheltered bay.

Keppel Bay is exposed to the prevailing south-east trades (strongest April-September) and to summer northerlies. The anchoring bay provides shelter from moderate south-easterlies, but the approach is open water and winds above about 20 knots or a large swell make it unworkable. Strong northerlies expose the bay.

Currents are generally mild. Best visibility July-October; humpback whales often pass in winter.

Descend from the anchor in the sheltered bay and follow the rock's gutters out to 15-18 m, working along the base of the rock. Turn at half air and return through the shallower coral gardens at 5-8 m, finishing with a safety stop near the anchor line.

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. Outer Rock is scheduled regularly in moderate conditions.