Cucumber Alley is the main site on Pellowe Reef, a small, isolated reef near the edge of the continental shelf. Because it sits further out and is visited only in suitable weather, Cairns Dive Adventures describes the reef as relatively untouched, with fantastic visibility and wonderful soft- and hard-coral cover. Silverswift describes Cucumber Alley as a wall dive at the shelf edge that drops quickly to 30 m in places, with the possibility of strong currents, and names it after the sea cucumbers that lie on the sand and rubble at the foot of the reef.

The shelf-edge position is what makes the dive. Deep, clear water close to the reef brings in large pelagic fish: schools of giant trevally, chevron barracuda and jacks, grey and whitetip reef sharks, and occasionally dolphins and rays. Dive the World reports Napoleon wrasse over 2 m long and nearly 200 kg, and bull rays up to 2 m.

On the wall itself there are moray eels, octopus, squirrelfish, sergeant majors, clownfish in anemones and plenty of nudibranchs. Most diving on Pellowe takes place between 5 and 20 m, so divers need not go deep to see the action, but the combination of current, a wall into deep water and occasional surface chop makes it better suited to divers with some experience or an Advanced certification. When conditions line up it is one of the most exciting dives on the southern Cairns reefs.

Because weather limits access, many regular Cairns divers have never been, and a calm-day visit is worth waiting for.

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 61 km out through Trinity Inlet and across the lagoon to Pellowe Reef takes around 82 minutes on a fast catamaran and noticeably longer on slower dive boats or into a south-easterly chop.

Pellowe is visited by Silverswift, Passions of Paradise and the Pro Dive Cairns liveaboard only when the weather allows, as it is small and exposed. Enter from the stern and descend promptly.

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. Pellowe is small, isolated and near the shelf edge, so it has little shelter: operators only go there on calm or moderate days, and strong current can run along the wall, particularly on spring tides. Its position gives some of the best visibility of the Cairns reefs.

Descend promptly to the wall and assess current. Follow the wall at 15-20 m (the reef drops quickly to 30 m in places) with the current if the guide plans a drift, watching the blue for pelagics. Rise to the reef top at 5-8 m for the second half and deploy a marker for the safety stop if drifting.

Silverswift – day trips in suitable weather; Pro Dive Cairns – liveaboard; Passions of Paradise – occasional; Pellowe is visited only on calm days, so trips there are opportunistic rather than scheduled; the mooring used on any day is chosen by the skipper according to wind, tide and other boats