City Hall is the showpiece certified dive from the Sunlover pontoon on Moore Reef. It is a large coral pinnacle that rises from the reef slope to within a few metres of the surface, riddled with at least ten swim-throughs, and with giant gorgonian fans on its deeper flanks. Diveplanit describes it as home to red cardinalfish, glassfish, coral trout, yellowtail fusiliers and damsels, and notes a remarkable resident turtle population: guides have counted 18 turtles, two hawksbills and sixteen greens, living on or around the pinnacle.

That is the main reason people remember the site. Turtles are seen on most dives, often resting in the swim-throughs or wedged into crevices, and they are accustomed to divers. The swim-throughs are large and straightforward, but divers should keep good buoyancy and avoid touching the walls.

Glassfish and cardinalfish fill the darker passages, coral trout and cod lurk under ledges, and fusiliers swirl around the top. The gorgonians at depth carry feather stars and small crustaceans. Moore Reef is a large horseshoe reef whose western side is sheltered in the prevailing south-easterly winds, which is why three pontoon operators are based there, and City Hall benefits from that shelter.

Depths are limited to the operator's maximum for certified dives, 18 m, which suits Open Water divers, and the site is close enough to the pontoon that no long swim is needed. It is a good dive for anyone doing a pontoon trip who wants more than the coral garden alongside the platform. Photographers should bring a wide-angle lens for the turtles and the fans.

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 47 km out through Trinity Inlet and across the lagoon to Moore Reef takes around 90 minutes on a fast catamaran and noticeably longer on slower dive boats or into a south-easterly chop.

Sunlover's catamaran runs daily to its permanently moored pontoon on Moore Reef, and certified divers are taken from the pontoon to City Hall by the dive team; there is no need to bring gear. Entry is from the pontoon's dive platform or tender.

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. Moore's horseshoe shape shelters its western side in south-easterlies, so the pontoons run in most weather short of a gale or cyclone. City Hall lies near the pontoon on the sheltered side of the reef and is dived most days.

Descend beside the pinnacle to the base at 15-18 m to see the big gorgonian fans, then spiral up and around it, using the swim-throughs at intermediate depths. Look for turtles resting in the crevices. Finish on the pinnacle top with a safety stop at 5 m before returning to the pontoon.

Sunlover Reef Cruises – daily pontoon trips; certified dives guided from the pontoon (to 18 m, about 50 minutes); Moore is also home to the Sunlover, Reef Magic and Great Adventures pontoons, and is visited by Passions of Paradise and Pure Snorkelling; the mooring used on any day is chosen by the skipper according to wind, tide and other boats