Cod Wall is the Flinders Reefs site Mike Ball highlights on its Yongala & Coral Sea expedition. The operator describes the ancient 'Gigantus Gorgonia' fan spanning more than 5 m, decorated with soft coral trees and sea whips, with visibility averaging 40 m or more. Its Coral Sea Odyssey materials describe Flinders more broadly as vertical walls dropping more than 300 m, with soft corals, massive sea fans, sharks, tuna and barracuda. Marinelife.org.au lists Cod Wall as a related site near China Wall.

The giant gorgonian is the centrepiece: a single sea fan more than 5 m across, estimated to be very old given the slow growth of these colonies, spread across the current on the wall. Around it, soft coral trees in reds, pinks and purples and long sea whips cover the face, and the wall falls away beneath into deep water.

The name suggests potato cod, which are found at several Coral Sea sites, and the Flinders area supports sharks, tuna and barracuda along its walls. Cruising the Edge reports tiger sharks, tawny nurse sharks and yellowfin and dogtooth tuna in the area. Anthias swarm along the face and hawkfish perch on the fans.

Cod Wall suits intermediate divers comfortable on a wall. The giant fan's depth is not published, so confirm it with the crew before descending, and take care not to touch this remarkable colony.

Liveaboard only, from Townsville. Mike Ball's Spoilsport visits Flinders on its 7-night Yongala & Coral Sea expedition (depart Breakwater Marina, Townsville, Thursday evening, finish in Cairns) and the 10-night Coral Sea Odyssey; the overnight crossing is about 140 nautical miles (260 km), passing Myrmidon Reef on the outer Great Barrier Reef. Private expedition yachts anchor behind the main sand cay in about 30 m over sand.

Cod Wall is on Mike Ball's Yongala & Coral Sea itinerary and is dived from a mooring or tender drop.

The Flinders Reefs lie about 250 km off the Queensland coast, roughly 140 nautical miles north-east of Townsville, beyond the outer Great Barrier Reef. The crossing is made overnight through open ocean and is uncomfortable in SE trades over about 20 knots (common June–August). The main sand cay gives some shelter from the trades, and the lagoon pinnacles are more protected than the outer walls.

Currents can be strong through the reef gaps and over the mid-reef bommies. September–December usually gives the calmest seas and 40 m-plus visibility; December–April is cyclone season.

Descend to the giant gorgonian (depth as briefed), then follow the wall past soft coral trees and sea whips, watching for potato cod and sharks. Ascend gradually along the wall and finish on the reef top.

Mike Ball Dive Expeditions (Spoilsport) – 7-night Yongala & Coral Sea (Townsville–Cairns) and 10-night Coral Sea Odyssey, a few departures a year; otherwise private expedition yachts only. Cod Wall is named on the Yongala & Coral Sea itinerary.