Nonki Bommie is the signature dive of Holmes Reef and one of the best-known soft-coral dives in the Coral Sea. It is a huge pinnacle split by a crack into two fingers, with a canyon between them. Marinelife.org.au gives a depth range of 5–36 m and a position of 16°32.030'S 147°48.324'E, and notes that the base continues to about 40 m before a wall drops to 300 m.

The pinnacle is draped in soft corals, giant yellow and red sponges and sea fans, with the largest fans in the deeper areas. Mike Ball's 7-night itinerary promises giant yellow and orange sea fans, with sharks patrolling the 35 m pinnacle, and the Coral Sea Odyssey describes huge, brightly coloured soft corals, fans, critters and schooling fish. The canyon between the two fingers is the photographic highlight, a narrow gap lined with colour.

Fish life is abundant. Big-eye trevally school around the bommie, dogtooth tuna and grey reef sharks patrol, silvertips appear, and hammerheads are an occasional visitor. On the bommie itself look for hawkfish, parrotfish, rabbitfish, butterflyfish, clownfish, nudibranchs and turtles. Dive the World calls it usually calm and one of the easier dives at Holmes, which is why it is used on every Holmes itinerary.

Nonki suits intermediate divers comfortable at 20–30 m. It is best for wide-angle photography, particularly in the canyon and around the fans, though macro subjects are plentiful. On Mike Ball's Townsville departures it is often the first Coral Sea dive after the overnight crossing, a spectacular introduction to the region's soft corals.

Liveaboard only. Mike Ball's Spoilsport includes Holmes Reef on its 7-night Coral Sea exploratory (Cairns return), the 7-night Yongala & Coral Sea expedition (Townsville to Cairns) and the 10-night Coral Sea Odyssey; the overnight crossing from Cairns is about 240 km of open ocean. Holmes is normally allocated a day on these itineraries.

Nonki Bommie is the signature Holmes site on all three itineraries and is dived from a mooring at the published position (16°32.030'S 147°48.324'E).

Holmes Reef is a pair of isolated Coral Sea atolls about 240–250 km east of Cairns with no land for shelter. Dive the World calls it a fair-weather destination: SE trades over about 20 knots (common June–August) make the crossing and surface conditions rough, although the lagoons and western sides offer some protection. Currents are normally gentle but can be strong in the channels and on the ridges, especially on a falling tide.

September–December usually has the calmest seas and 20–40 m visibility; December–April is cyclone season.

Descend the mooring to the canyon between the two fingers at 25–30 m, admire the giant sea fans at the base, then circle one finger and cross to the other, ascending gradually. Finish on the top at 4–6 m among the soft corals and anthias for a safety stop.

Nitrox useful to extend time in the 25–30 m canyon.

Mike Ball Dive Expeditions (Spoilsport) – 7-night Coral Sea exploratory (Cairns), 7-night Yongala & Coral Sea (Townsville–Cairns) and 10-night Coral Sea Odyssey; a few departures a year include Holmes. Nonki is the main Holmes dive on every one.