Monolith is a wall dive on the sheltered side of the Ribbon Reefs, and Spirit of Freedom describes it as the neighbour of Challenger Bay. The defining feature is an impressive field of fist coral (Pocillopora and similar knobbly species) that cascades down the reef face, creating a textured slope unlike the branching gardens elsewhere on the Ribbons.

The wall drops from a shallow reef top to around 30 m. Along its face, crevices and ledges shelter rock lobsters, barramundi cod and moray eels, and giant clams sit among the coral. Nudibranchs are plentiful on the reef face. The site's wildcard is the chance of hammerhead sharks passing along the wall; Spirit of Freedom lists hammerheads among its regular sightings, so keep an eye on the blue.

Because Monolith lies next to Challenger Bay and Gotham City, the broader fish community is similar: trevally, red bass, sweetlips, fusiliers and whitetip reef sharks, with the chance of turtles and rays. The name refers to a large block-like section of reef. The wall is simple to navigate, and the fist-coral field makes a striking backdrop for wide-angle images.

Monolith suits intermediate divers comfortable on a wall. It is often used as a daytime alternative when Challenger Bay has been dived at night, giving guests a different perspective on the same reef system. Detailed published descriptions are scarce, so depths are indicative and should be confirmed with the crew briefing. On a clear day the light falling across the textured slope makes this one of the more photogenic walls in the 9½ area.

Liveaboard only (or fly-dive via Lizard Island). Mike Ball Dive Expeditions' Spoilsport and Spirit of Freedom depart Cairns (Trinity Wharf / Marlin Marina) in the evening and steam north overnight, roughly 12–14 hours and 200–250 km, to reach the Ribbon Reefs by morning; some itineraries fly Cairns–Lizard Island (about one hour, scenic flight along the coast) and board or disembark there. Trips run 3–7 nights and include Monolith on Spirit of Freedom itineraries.

Divers enter by giant stride from the dive deck at the mooring and descend the mooring line. Spirit of Freedom describes it as the neighbour of Challenger Bay, so it is often dived from the same overnight mooring area.

The Ribbon Reefs sit on the edge of the continental shelf and take the full south-east trade wind from April to October. Lagoon-side moorings stay diveable in 20–25 knot SE winds, but reef-front sites and passes need lighter winds; liveaboards shelter behind the reefs overnight. September to December is usually calmest.

Tidal flow through the gaps between the Ribbons is strong on springs, so exposed pinnacles are timed for slack water. December to April brings rain, lower visibility and cyclone risk; box jellyfish and Irukandji are possible November to May. Monolith shares the relative shelter of Challenger Bay, but hammerheads are more likely when there is some current off the wall.

Descend to 18–20 m on the wall, follow it with the reef on one side while watching the blue for hammerheads, turn at half gas and ascend over the fist-coral field for a safety stop at 5 m.

Spirit of Freedom – 3-, 4- and 7-night Ribbon Reef trips from Cairns/Lizard Island.