The Coral Greenhouse is the centrepiece of the Museum of Underwater Art (MOUA), the first underwater museum in the southern hemisphere. Designed by the British sculptor Jason deCaires Taylor and installed on John Brewer Reef in 2020, it holds the Guinness World Record as the largest underwater art structure: a 12 m tall, 58-tonne 'greenhouse' of corrosion-resistant stainless steel and pH-neutral cement sitting in about 16 m of water. The structure is a stylised glasshouse frame with open panels, so divers can swim around and look inside rather than penetrate it.

Inside stand figurative sculptures of 'reef guardians', modelled on local Townsville school children, tending planter boxes, while sculpted 'floating trees' based on local species rise alongside. The whole thing was designed as a substrate for coral and invertebrate settlement, and after several years it is steadily colonising – sea squirts, soft corals (Dendronephthya), sponges and algae soften the lines, and reef fish have moved in. Batfish, damsels, butterflyfish and schooling fusiliers are regulars, with turtles and reef sharks in the surrounding reef.

John Brewer Reef has its own history. In 1988 the seven-storey, 200-room Four Seasons Barrier Reef Resort, a floating five-star hotel, was moored here; it lasted barely a year before being sold and towed to Vietnam. The reef suffered crown-of-thorns outbreaks in the early 2000s and severe bleaching in 2016, and MOUA's installation was partly intended to draw attention to reef health and to support restoration work by Reef Ecologic and others.

Because the Greenhouse sits in a sheltered, low-current area at modest depth, it suits new divers and even competent freedivers, while photographers get a striking subject. Snorkellers can see the top of the structure in good visibility but get more from the Ocean Sentinels nearby. It is a no-touch site: treat the sculptures like coral.

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. Yongala Dive (Alva Beach) and Orpheus Island Lodge also run MOUA day trips, and Coral Expeditions includes the site on its 10-night Brisbane–Cairns cruises.

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.

Descend to the sand beside the Greenhouse at about 16 m, circle the outside of the structure, then look through the openings at the figures and planter boxes inside. Rise to the upper sections at 8–10 m, then swim to the nearby coral bommies and the Ocean Sentinels (5 m) for the last part of the dive and safety stop.

Adrenalin Snorkel & Dive (Townsville/Magnetic Island) – regular day trips to John Brewer Reef and MOUA, the reef most frequently chosen; Yongala Dive (Alva) – MOUA day trips; Orpheus Island Lodge – guest day trips; Coral Expeditions – liveaboard cruise stop.