Passage Rocks lies in a deep north-south channel on the northern side of Great Keppel Island, and it is described by the regional tourism body as having more hard coral species than any other site in the Keppels. The rocks provide a range of habitats, from exposed faces swept by current to sheltered pockets, which helps explain the diversity. Snorkellers and divers find hard corals of many types, including branching, plate, massive and encrusting forms, along with feather stars clinging to the rocks and a good abundance of fish.

The water movement through the channel brings food, and larger fish such as trevally and mackerel may pass through. Because the channel carries tidal flow, timing is important. Near slack water, the rocks can be explored comfortably; at mid tide, the current can be strong enough to make snorkelling hard work.

The channel itself is deeper, and divers should stay close to the rocks rather than drifting into mid-channel. Passage Rocks is less visited than Monkey Beach or the Middle Island sites, partly because of the tidal factor and partly because access is only by boat or kayak. For divers interested in coral diversity, however, it is one of the most rewarding shallow sites around Great Keppel.

It suits confident snorkellers and Open Water divers with some experience of current, and is best visited with local guidance on the day's tides.

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. Passage Rocks is on the northern side of Great Keppel, reached by boat (about 10-15 minutes from Fisherman's Beach) or by experienced kayakers in calm weather.

Boats anchor on sand clear of the channel.

Keppel Bay is exposed to the prevailing south-east trades (strongest April-September) and to summer northerlies. Passage Rocks sits in a deep north-south channel, so tidal flow is the main factor: dive or snorkel near slack water. The northern side of the island is sheltered from south-easterlies but exposed to northerlies.

Visibility 5-12 m.

Enter near slack water on the sheltered side of the rocks and follow the rocky reef around, keeping out of the main channel flow. Explore the hard coral and feather stars at 4-10 m and return before the tide starts to run.

Visited by private boats, kayakers and occasionally by Keppel Dive & Water Sports or Keppel snorkel cruises; no fixed schedule.