Lighthouse Bommie is a small, totem-pole-like coral pinnacle rising from about 24–30 m to within 5 m of the surface near the southern end of Ribbon Reef No. 10. It is one of the most consistently productive sites on the Ribbons and the headquarters of the dwarf minke whale season. Nigel Marsh's reports for Scuba Diver and Divernet call it the place where up to a dozen minkes can be encountered in June, with fewer in July.

The pinnacle itself is modest in size, and Mike Ball's guides note coral growth is mostly limited to the top, with a larger mound nearby at around 15 m. What makes it special is the density of life. Schools of big-eye trevally, chevron barracuda, yellow-lined snapper, fusiliers and surgeonfish swirl around the column, grey reef sharks and Malabar groupers patrol, and green and hawksbill turtles use a cleaning station on the bommie, with more visiting at night. At least three olive sea snakes are resident. For macro, look for mantis shrimp, octopus, flame file shells, pipefish, scorpionfish, longnose hawkfish and several anemonefish species. In summer, manta rays use the adjacent mound as a cleaning station, and glassfish swarms draw in predators; in winter eagle rays pass south of the mound.

The minke encounters are run under a GBRMPA code of practice. Swimmers hold onto a surface line streamed from the stern; whales approach on their own terms, and divers who meet a whale underwater simply carry on. Most close encounters happen while snorkelling. Mike Ball has run minke expeditions since 1996 and reports encounter rates above 90 per cent.

The dive suits all levels, though its open-water position means you need to hold your depth without a wall for reference. It is often dived twice on a trip because there is too much to see in one go.

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 Lighthouse Bommie on most Ribbon Reef and all minke-whale itineraries.

Divers enter by giant stride from the dive deck at the mooring and descend the mooring line. The pinnacle has a mooring close by and is often dived twice on a trip. During June and July it is the main base for dwarf minke whale encounters, with surface lines streamed from the stern.

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. Lighthouse Bommie is an open-water pinnacle, so it is dived in light to moderate winds and at lower tidal flow.

Winter (June–July) brings the minke whales but also the strongest trades and a lumpy surface.

Descend to the base of the pinnacle at 20–24 m and check the mound beside it for mantas (summer) or eagle rays (winter). Then spiral slowly up the pinnacle, stopping at the turtle cleaning station and searching for macro. Finish on the top at 5 m for the safety stop.

In minke season, stay near the stern lines for the ascent.

Mike Ball Dive Expeditions (Spoilsport) – Ribbon Reef, Cod Hole and Coral Sea itineraries from Cairns, several departures a month; Spirit of Freedom – 3-, 4- and 7-night trips from Cairns/Lizard Island, weekly. Both hold GBRMPA permits for swim-with dwarf minke whale encounters in June–July.