Watanabe Bommie is a deep pinnacle in the Flinders Reefs, about 250 km off the Queensland coast. Marinelife.org.au describes it as an office-block-sized pinnacle with a depth range of 12–40 m, covered in soft corals, gorgonians and sea whips, and surrounded by schools of pelagic fish and sharks. The name's origin is not documented in the sources consulted.

The top of the bommie lies at about 12 m, so there is no shallow reef to linger on, and the structure falls steeply to around 40 m. Its sheer size gives it the presence of a building in the blue. Soft corals in reds, pinks and purples cover much of the surface, gorgonian fans spread across the current, and sea whips extend from the walls. Visibility in the Flinders area often exceeds 40 m, so the whole structure can sometimes be seen from above.

Isolated pinnacles in open water concentrate life, and Watanabe is no exception. Schools of trevally, barracuda, fusiliers and snapper circle the bommie, and grey reef, whitetip and silvertip sharks patrol. Cruising the Edge, describing Flinders more generally, lists tiger sharks, tawny nurse sharks and yellowfin and dogtooth tuna, so larger visitors are possible.

The dive suits advanced divers comfortable with depth, open-water descents and ascents, and possible current. The top at 12 m means most of the dive is spent below 15 m, so gas and no-decompression limits need watching; nitrox helps. Flinders is visited by Mike Ball only a few times a year, and Watanabe Bommie is one of the dives that justifies the long crossing.

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.

Watanabe Bommie is dived from a mooring or anchorage near the pinnacle; descent is straight to the top at about 12 m.

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 directly to the top of the pinnacle at 12 m and on down the up-current face to 25–30 m, circle the bommie watching for pelagic schools and sharks, then spiral back up and complete the safety stop on the top or the line.

Nitrox recommended; plan conservatively given the depth and remoteness.

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.