Pretty Patches is a lesser-known patch reef between Arlington Reef and Michaelmas Cay, made up of three separate patches with shallow lagoons, according to Tusa Reef Tours. Tusa and Passions of Paradise are the only two companies permitted to dive the location, which is one reason Passions describes it as very untouched. Passions adds that the reef is isolated, that its bommies are tightly grouped, that turtles are common and coral cover is excellent, and that depths reach about 18 m; it visits only in light summer winds.

Tusa describes breathtaking underwater formations, with staghorn corals, sea fans, spaghetti corals, leather mushroom corals and brain corals. The tight grouping of the bommies means divers are constantly moving between coral heads, through gaps and around corners, which makes the dive feel intricate and full of discovery. The lagoons between the patches are shallow and bright, good for snorkellers and for photographers who want colour.

Because so few boats use it, the coral shows little sign of diver damage, and the fish are relatively relaxed. Beyond turtles, expect a typical mid-shelf community of parrotfish, damsels, wrasse, butterflyfish, angelfish and coral trout, with reef sharks possible on the edges. The depth is modest and the conditions calm when it is visited, so it suits all levels.

Coordinates for the patches are not published. It is a special stop for Cairns regulars, as it is available only on selected days. Visibility is typically 10-18 m on the calm days when it is visited, and often better.

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 40 km out through Trinity Inlet and across the lagoon to Pretty Patches takes around 80 minutes on a fast catamaran and noticeably longer on slower dive boats or into a south-easterly chop.

Only Tusa Reef Tours and Passions of Paradise are permitted to use Pretty Patches, and Passions visits only in light summer winds. 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. Being closer to the coast, visibility is lower than on the outer reefs, especially after rain. Passions notes that it visits only in light summer winds; Pretty Patches is isolated and exposed in the south-easterly trades.

Descend among the tightly grouped bommies and weave between them at 8-15 m, then explore the shallow lagoons and their coral formations before a safety stop on a bommie top.

Tusa Reef Tours and Passions of Paradise – the only two permitted operators; Passions visits only in light summer winds