Clam Bay is a long, curving bay on Great Keppel Island's southern side, about 2 km from end to end and divided into four beaches. The first beach is about 200 m long and the main beach 550 m. In front of them a broad reef flat extends 100-150 m offshore before dropping to the reef edge, where most of the interest lies.

The reef is a known breeding ground for coral trout, and snorkellers report juvenile coral colonies, anemones with their fish, and turtles feeding on the flat. Giant clams, which gave the bay its name, can still be found among the coral. Depths at the reef edge are only a few metres, so this is primarily a snorkelling site, although it can be dived as a shallow, exploratory shore dive.

Unlike Monkey Beach, Clam Bay faces the prevailing south-easterly trade winds and is often windy; it comes into its own on northerly or easterly days when the western bays are rough. Timing with the tide is important, since the long reef flat must be crossed to reach the edge and it becomes very shallow at low water. Clam Bay is less visited than the reefs near Fisherman's Beach because access is mainly by boat, which gives it a quieter feel.

It suits snorkellers and new divers with a boat at their disposal, and those staying on the island who want to explore beyond the busy beaches. Treat the reef flat with care: much of the young coral growth is right at the surface on lower 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. Clam Bay is on Great Keppel's southern coast and is most easily reached by private boat, water taxi or the dive operator's boat, about 10-15 minutes from Fisherman's Beach; a walking track exists but is long.

Land on the main (550 m) beach and enter at mid to low tide, swimming out across the reef flat to the reef edge 100-150 m offshore.

Keppel Bay is exposed to the prevailing south-east trades (strongest April-September) and to summer northerlies. Clam Bay faces south and is best in northerly or easterly winds; the prevailing south-easterlies blow into the bay and make it windy and choppy, so it is less often suitable during the trade-wind season. Enter at mid to low tide when the reef edge can be reached; at dead low the reef flat is too shallow to cross without damage.

Visibility is modest and poor after rain. Summer stingers possible.

Cross the reef flat on the surface at mid tide to the reef edge, then snorkel or dive along the edge in 2-5 m, looking for juvenile corals, anemones and coral trout. Return to the beach before the tide drops too far to re-cross the flat.

Visited by private boats, water taxis and occasionally Keppel Dive & Water Sports or Keppel cruise operators; no scheduled dive operation.