The Cluster is a group of four large bommies arranged in the shape of a cross on Bait Reef, described by the North Queensland Underwater Explorers Club as a night-dive location and a turtle resting ground. 100 Magic Miles lists 'Cluster of Four' among the named stones of the Stepping Stones, which suggests the Cluster is part of, or adjacent to, that line of pinnacles; the sources do not give a precise position. Its compact layout makes it ideal for night diving. Four bommies close together give divers a simple navigation problem – circle one, cross to the next – with the boat's lights overhead and no long swims into darkness.

At night turtles sleep wedged under ledges on the bommies, parrotfish rest in mucus cocoons, painted crayfish and slipper lobsters emerge, and feather stars open to feed. By day the same bommies carry the rich coral and fish life of Bait Reef: sweetlips, cod, coral trout, wrasse and schools of fusiliers. The Cluster is sheltered compared with the reef's exposed walls, and current is usually mild, although it can pick up around the bommies on spring tides.

Depths are moderate, with bommie tops shallow enough for safety stops. Because night dives on Bait Reef require an overnight vessel, the Cluster is mostly dived from liveaboards and overnight charters out of Airlie Beach. Day-trip boats may also include it when they moor near the Stepping Stones.

Divers should not touch or shine torches directly at sleeping turtles for long periods. It is in the Bait Reef green zone.

Boat only. Bait Reef lies on the outer Great Barrier Reef about 32 km north-east of Hayman Island and 11.5 km west of Hardy Reef – roughly 1.5–2 hours by fast dive boat from Airlie Beach (Coral Sea Marina/Port of Airlie) or from Hamilton Island marina. Explore Group runs Great Barrier Reef scuba day trips to Bait Reef from both Airlie Beach and Hamilton Island; Whitsunday Dive Adventures also lists Bait Reef, and overnight/liveaboard vessels from Airlie include it.

Parking at Airlie is available near the marinas. Private vessels must use public moorings (Bait Reef is a green zone with no-anchoring areas) and need a settled forecast for the open-water crossing. As a night dive, it is visited from liveaboards or overnight vessels moored at Bait Reef.

Bait Reef sits in open water on the outer shelf and is fully exposed to the south-east trades (15–25 knots April–September); day trips are cancelled or diverted to the islands in strong wind warnings, and the crossing is rough above about 20 knots. The calmest windows are September–December and the occasional winter high. Visibility is usually 10–25 m, often 30 m on calm neap days, and is little affected by coastal run-off.

Tidal currents run along the outer walls and through the gullies, strongest on spring tides; strong southerly winds create challenging currents on the southern face and Manta Ray Drop-off – plan for slack water and neap tides. Manta rays are most common May–September. Marine stinger season (box jellyfish and Irukandji) runs roughly November to May – wear a full-length stinger suit or wetsuit with hood and gloves, carry vinegar.

Cyclone season November–April; tropical lows and cyclones can close sites and damage coral (TC Yasi 2011, TC Debbie 2017).

Descend to the centre of the cross and circle each of the four bommies in turn at 8–18 m, looking under ledges for resting turtles; finish on a bommie top. At night, stay close to the bommies with a torch and keep the boat's lights in view.

Liveaboard and overnight vessels from Airlie Beach (night dives); Explore Group day trips may visit by day. Nearest dive centres for gear hire, fills and local advice: Explore Group, Whitsunday Dive Adventures, Cruise Whitsundays, Red Cat Adventures.