Swimming Pools is a pair of moorings on Milln Reef, Swimming Pools I and II, that Pro Dive Cairns lists as separate sites but which share the same character: coral outcrops and small bommies scattered over a sandy seabed at an average depth of about 10 m, with the deepest point around 21 m near an outer bommie. The name reflects how the sheltered sand patches between the coral look from the surface on a calm day. The layout is relaxed and easy, suiting divers of all levels and making it a good choice for a check-out or refresher dive.

The signature sight is the schools of diagonal-banded sweetlips that hang in the shelter of the bommies, often dozens together, and Pro Dive Cairns also highlights nudibranchs, which can be found on almost every outcrop. The outer bommie is decorated with gorgonian fans. Turtles are frequently seen, barracuda cruise over the sand, and bull rays or cowtail rays rest on the bottom.

Among the coral heads look for coral trout, anemonefish, parrotfish and damsels, and for garden eels and gobies on the sand. At night the Pools are an easy, rewarding site, with sleeping parrotfish, hunting barracuda and turtles, and plenty of crustaceans. The shallow tops of the outcrops are suitable for snorkellers when the tide is up.

Because the two moorings are close together, the skipper chooses whichever is free and better sheltered on the day; the diving is essentially the same. Both moorings are well suited to a first dive after the long run out, and to divers who want to practise buoyancy over sand without worrying about depth.

Boat access only. Cairns day boats leave from the Reef Fleet Terminal (1 Spence Street) and the neighbouring Marlin Marina on the city waterfront, with check-in between about 7:00 and 8:00 am; most operators run transfers from city and northern-beaches accommodation, and there is paid parking near the terminal. The run of about 55 km out through Trinity Inlet and across the lagoon to Milln Reef takes around 76 minutes on a fast catamaran and noticeably longer on slower dive boats or into a south-easterly chop.

Swimming Pools I and II are neighbouring moorings used by Silverswift, the Pro Dive Cairns liveaboard and other Milln day boats. Enter from the stern platform.

The prevailing south-east trade winds (typically 15-25 knots from April to September) are what limit Cairns outer-reef diving: above about 25 knots trips may be cancelled, and exposed eastern moorings are used only in light winds. Summer northerlies are gentler but make north-facing moorings choppy. Box jellyfish and Irukandji are present from about November to May (stinger suits on every dive), and the cyclone season runs November to April, when a system in the Coral Sea can close the reef for days.

Visibility drops after heavy rain and strong winds; spring is usually calmest and clearest. The Pools are sheltered sand-and-bommie moorings suited to most trade-wind days; visibility may drop over the sand when a swell is running.

Descend to about 10 m and work from bommie to bommie across the sand, heading for the outer bommie with the gorgonian fans (15-21 m) first. Turn at a third of your gas and return via the shallower outcrops, looking for sweetlips schools and nudibranchs, with a safety stop near the mooring.

Silverswift – daily day trips (Milln is one of its core reefs); Passions of Paradise – daily sailing-catamaran trips to Milln moorings; Pro Dive Cairns – 3-day/2-night liveaboard including Milln night dives