Kate's Cathedral is one of the lesser-known moorings on the Ribbon Reefs, listed on Mike Ball Dive Expeditions' Cod Hole–Ribbon Reefs itinerary map among the Ribbon Reef No. 10 sites alongside Lighthouse Bommie, Pixie Pinnacle, Vertical Gardens, Goggle Gardens and the Cod Hole. Mike Ball has named and dived these reefs for more than 30 years, and its map is the most complete public list of Ribbon Reef moorings.

Beyond the name and general location, there is no published description of the site in the sources consulted. The name suggests an arch, cavern or overhanging reef structure, a common feature along the lagoon side of the Ribbons, where coral buttresses and bommies form swim-throughs and caverns. If that is the case, divers can expect overhangs lined with soft corals and gorgonians, with glassfish and sweepers in the darker sections, the pattern seen at comparable sites such as Pixie's Caves.

The surrounding reefs share the fauna of Ribbon Reef No. 10: green turtles, whitetip and grey reef sharks, schooling fusiliers and trevally, groupers and coral trout, anemonefish, nudibranchs and, in June and July, dwarf minke whales that range across the whole reef. Water temperatures, visibility and conditions match the neighbouring sites.

Kate's Cathedral is best treated as an occasional alternative mooring that the crew uses when conditions or crowding rule out the better-known sites. Divers keen to log it should ask the cruise director early in the trip, since the crew plans moorings day by day around wind, tide and the whereabouts of other vessels.

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 Kate's Cathedral on some Mike Ball itineraries.

Divers enter by giant stride from the dive deck at the mooring and descend the mooring line. The site appears on Mike Ball's itinerary map among the Ribbon Reef No. 10 moorings (with Lighthouse Bommie, Pixie Pinnacle and the Cod Hole); it is used at the crew's discretion depending on weather and whale activity.

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.

No published dive plan. Expect a standard Ribbon Reef moored dive: descend the mooring, follow the crew briefing for the route around the reef structure, turn at half gas and complete a safety stop on the reef top.

Mike Ball Dive Expeditions (Spoilsport) – occasional stop on Cod Hole–Ribbon Reef itineraries.