Arlington Reef is one of the largest reef systems in the Cairns section of the Great Barrier Reef Marine Park, a broad platform reef lying between Green Island and Michaelmas Cay about 35 km north-east of the city. Despite its size it is less prominent on dive itineraries than the outer reefs, and today most divers see it on a half-day pontoon trip. The Sunlover half-day tour spends three hours at a pontoon moored in sheltered water just metres from the reef, with a submerged platform for easy entry.

Cairns Dive Adventures describes large coral gardens with many different species of soft and hard corals, and lists giant Maori wrasse, potato cod, anemonefish, glassfish, cuttlefish, sea turtles and giant clams among the wildlife. Certified dives go to a maximum of 15 m for about 40 minutes, introductory dives usually no deeper than 8 m, and helmet diving and snorkelling are also offered. The potato cod are worth noting: these large, spotted groupers are curious and often approach divers closely.

The trip suits people with limited time who want a short reef experience, and families where not everyone dives, rather than experienced divers seeking multiple deeper dives. Being closer to the coast than the outer reefs, Arlington's visibility is typically lower and falls after rain. Some Arlington sites are also used by private charters and sailing boats.

Pretty Patches, a separate isolated patch reef between Arlington and Michaelmas, has its own entry. The short trip makes it a practical option for travellers with an afternoon flight, bearing in mind the 12-24 hour no-fly interval after diving.

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 35 km out through Trinity Inlet and across the lagoon to Arlington Reef takes around 75 minutes on a fast catamaran and noticeably longer on slower dive boats or into a south-easterly chop.

Sunlover runs a half-day Arlington Reef pontoon trip (departing about 8:00 am and returning about 1:30 pm, with three hours at the pontoon), mainly in the high season. The pontoon's submerged platform allows easy water entry; gear is supplied.

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. The pontoon is in sheltered water beside the reef and operates in most conditions; the half-day trip is not run every day outside peak periods.

Guided certified dives descend from the pontoon's submerged platform to 10-15 m along the reef edge and return through the coral gardens for a safety stop near the pontoon. Introductory divers stay above about 8 m with an instructor.

Sunlover Reef Cruises – half-day pontoon trips (certified dives to 15 m, introductory dives to about 8 m, helmet dives), mainly in the high season; private charters occasionally