The Canyons on Hardy Reef are, in 100 Magic Miles' words, an 'endless maze of tunnels, canyons and shallow caves' reaching up to the surface. The guide gives depths of 3–18 m and visibility of 10–20 m. It is a site for divers who like structure: rather than a wall or slope, the reef here is honeycombed with passages, and a dive becomes a wander through a coral labyrinth.

Life in the canyons is concentrated in the shade. The guide notes crayfish and morwong – more than 100 in a single cave – along with large and small reef fish. Soft corals and sponges grow on the canyon walls where current brings food, and hard corals cover the tops.

Light filtering into the shallow caves creates good photographic conditions. The canyons provide shelter, but the guide warns that current outside them is strong, and snorkelling over the reef flat can be hard work when it runs. Navigation takes care in a maze, and divers should stay with a buddy and guide, keep track of turns, and avoid disturbing silt in the caves.

Caves are shallow and open, but they are still overhead environments. No day operator lists the Canyons by name; it is most likely to be dived from liveaboards or charters working the Hardy–Line–Sinker complex, and possibly on guided dives from Reefworld when conditions allow. Coral condition since Cyclone Debbie has not been specifically documented.

For experienced Open Water divers, it offers one of the most interesting reef structures in the outer Whitsundays.

Boat only. Hardy Reef lies on the outer Great Barrier Reef roughly 80 km offshore from Airlie Beach and Hamilton Island. Cruise Whitsundays' high-speed catamarans depart Port of Airlie (Airlie Beach) daily, with connections from Hamilton Island and Daydream Island, and reach the Reefworld pontoon in about 2 hours; scenic flights (about 30 minutes) also land at the reef by seaplane or helicopter.

Paid parking is available at Port of Airlie. Divers book certified or introductory dives on board. Other Hardy sites and the neighbouring Line, Sinker and Fairey reefs are reached by liveaboards and private charters; private vessels must use public moorings and observe no-anchoring areas.

Hardy and its neighbours are outer-shelf reefs 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).

Current is strong outside the canyons and over the reef flat.

Enter the canyon system at 10–15 m and weave through tunnels and shallow caves, using the canyons for shelter from current; keep track of the route and exit to the boat side. Avoid the reef flat where current runs.

No regular day-trip operator; visited on liveaboard/overnight dive trips from Airlie Beach and private charters. Cruise Whitsundays' Reefworld is nearby on Hardy Reef.