Keeper Reef is one of the regular day-trip reefs off Townsville, used by Adrenalin Snorkel & Dive on its standard trips alongside John Brewer and Lodestone, and also scheduled as a 'special reef trip'. It lies close to Helix Reef and about 8 nm from Lodestone on the mid-shelf. The defining feature is the layout of its coral gardens: ridges of coral and bommies divide the reef into a genuine maze, with sandy channels and small swim-throughs, caves and canyons between them.

Divers commonly describe it as easy to get lost at, despite a maximum depth of only about 16–21 m, so good compass work and a buddy who pays attention are part of the experience. That same complexity makes it rewarding to explore – every turn opens a new gully or bommie, and fish shelter in the overhangs. Hard coral cover is healthy in the shallow gardens, with plate, branching and massive corals, and the reef top offers very good snorkelling – TripAdvisor reviewers of Adrenalin's trips single out Keeper for snorkelling.

Expect the usual mid-shelf cast: parrotfish, surgeonfish, fusiliers, coral trout, sweetlips, angelfish, anemonefish, turtles and reef sharks, with trevally cruising the edges. Keeper is mostly a shallow, gentle dive, which makes it well suited to newer divers, Discover Scuba and mixed groups, while experienced divers get plenty of topography to enjoy. It is not a deep or current-swept reef; the challenge is navigation rather than conditions.

Published information on Keeper is thinner than for John Brewer or Lodestone, and depths here follow dive-guide listings (to about 16–21 m).

Boat only. Adrenalin Snorkel & Dive departs the Fuel Wharf at Breakwater Marina, Townsville, at about 7:00 am and picks up at the Nelly Bay ferry terminal on Magnetic Island at about 7:50 am; the run out to the mid-shelf reefs (John Brewer, Lodestone, Keeper, Helix, Wheeler) takes roughly 2–2.5 hours each way depending on sea state, and the reef is chosen on the day to suit wind and tide. Paid parking is available around Breakwater Marina and the Townsville ferry terminals; Magnetic Island guests catch an early SeaLink ferry or walk to the Nelly Bay terminal.

Private boats launch at the Ross River or Townsville Breakwater ramps; the reefs are 70–90 km offshore, so a capable offshore vessel, EPIRB and a good forecast are essential. Use public moorings where installed and never anchor on coral.

The Townsville mid-shelf reefs sit fully exposed to the south-east trade winds, which blow 15–25 knots for long stretches from April to September. Operators generally cancel when winds exceed about 20 knots or a strong wind warning is current, and the 2–2.5 hour crossing is rough above 15 knots. The calmest windows are the late-spring and early-summer glassouts (October–December) and occasional winter high-pressure lulls.

Visibility is usually 12–25 m, dropping after big south-easterly blows and after wet-season floods from the Burdekin and Herbert rivers push turbid plumes offshore (January–April). 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).

Tidal currents around reef edges and bommies are strongest on spring tides; plan wall and pass dives near slack.

Take a compass bearing back to the boat before leaving the mooring. Explore the coral ridges and bommies at 8–16 m, working out and back on reciprocal headings rather than following the maze; use distinctive bommies as waypoints. Finish in the shallow coral gardens at 3–5 m under the boat.

Adrenalin Snorkel & Dive (Townsville/Magnetic Island) – day trips several days a week, reef chosen on conditions from John Brewer, Lodestone and Keeper, with Helix and Wheeler as scheduled 'special reef trips'; occasional liveaboard and private charters. Yongala Dive (Alva Beach) and Orpheus Island Lodge also run charters to MOUA/John Brewer.