Knuckle Reef lies on the outer Great Barrier Reef north-east of Airlie Beach, beyond Hardy Reef, and was for years home to a Cruise Whitsundays pontoon – 'Knuckle Reef Lagoon' – which carried day visitors for snorkelling, introductory dives and glass-bottom boat rides. Traveller reviews from the late 2000s and early 2010s describe the pontoon era, with mixed opinions. Cruise Whitsundays now concentrates on its Reefworld pontoon at Hardy Reef, and Knuckle Reef is visited today mainly on liveaboard and overnight trips such as Whitsunday Expeditions' 3-night voyages aboard SV Summer Jo, which list Knuckle among possible reefs.

Tour guides describe coral bommies, sandy lagoons and dramatic drop-offs, with shallow coral gardens suitable for snorkellers and deeper drop-offs for certified divers, and visibility often exceeding 20 m. Marine life includes sea turtles, reef sharks (black-tip and white-tip), manta rays, giant clams, parrotfish, clownfish, angelfish and moray eels. The lagoon's shelter makes it a comfortable site for new divers and for night dives from anchored vessels.

Being further offshore than Hardy, Knuckle benefits from clearer water but is correspondingly more exposed; trips depend on weather, and liveaboard operators choose between Knuckle, Bait, Black, Kennedy, Elizabeth, Seagull and Trigger reefs according to conditions. Detailed site maps and depths for Knuckle Reef are not published in the sources reviewed, and the date the pontoon was withdrawn is not confirmed. The reef's condition after Cyclone Debbie and later bleaching events has not been specifically documented.

For divers booking a liveaboard, it is worth asking whether Knuckle is on the likely itinerary, since its sheltered lagoon makes it a good choice for the first dive of a trip or for night diving.

Boat only, on overnight or multi-day trips. Whitsunday Expeditions/Explore Whitsundays' SV Summer Jo (100 ft) departs Port of Airlie, Airlie Beach, on 3-night voyages (Friday 4 pm to Monday 2 pm) and 6-day expeditions that choose between Bait Reef Lagoon, Black Reef, Kennedy, Elizabeth, Seagull, Trigger and Knuckle reefs according to weather, tide and visibility. The outer reefs lie roughly 75–90 km offshore – several hours by charter vessel – so private boats need long-range capability, a settled forecast and must use public moorings where available.

Parking at Port of Airlie.

Knuckle Reef is an outer-shelf reef fully exposed to the south-east trades (15–25 knots April–September). The large Reefworld catamarans run in most weather, but the crossing is rough in strong winds and diving can be restricted; smaller charter boats need a settled forecast. Hardy Reef's lagoon drains through a deep channel (about 60 m) beside the pontoon, and strong tidal currents run along the reef edges and through the gaps between Hardy, Line, Sinker and Fairey reefs, especially on spring tides and at the bottom of the tide – plan edge and wall dives for slack water.

Visibility is typically 8–20 m, up to 30 m on the outer faces. Marine stinger season (box jellyfish and Irukandji) runs roughly November to May – wear a full-length stinger suit or wetsuit with hood and gloves, carry vinegar. Cyclone season November–April; tropical lows and cyclones can close sites and damage coral (TC Yasi 2011, TC Debbie 2017).

Descend into the lagoon and explore the coral bommies and sandy patches at 5–12 m, then visit the reef edge and drop-off to 15–20 m if conditions allow. Finish in the shallow coral gardens.

Whitsunday Expeditions / Explore Whitsundays – SV Summer Jo 3-night voyages (weekly, Fri–Mon) and 6-day expeditions from Airlie Beach, site chosen on conditions; other overnight charters occasionally.