Flora Reef is a small submerged atoll in the Coral Sea, about 5 by 4 km, horseshoe-shaped and without islets. Marinelife.org.au notes a quick drop-off outside the lagoon, silvertip and grey reef sharks, and strange caves in the coral that resemble lava tubes, and warns that the reef is affected by current. It lies near Holmes Reef, roughly 200 km east of Cairns, and sees very few visitors.

The caves are the reef's curiosity. Formed within the coral structure, they are described as tubular passages resembling lava tubes, which is unusual for a coral reef, where caves are more often irregular chambers or overhangs. Their size and depth are not documented, and they should be treated as overhead environments.

Outside the lagoon, the reef drops steeply into deep water. Silvertips and grey reef sharks patrol the drop-off, and the usual Coral Sea pelagics, including trevally, tuna and barracuda, are likely. Hard and soft corals, fans and sea whips cover the walls where current flows. Visibility is typically excellent.

Flora is not on the itineraries of Mike Ball or Spirit of Freedom, and no dive site names were found. It is a site for self-sufficient expedition divers on a private charter, possibly combined with Holmes Reef. Divers planning a visit should carry full safety equipment and dive conservatively, as help is at least a day away.

There is no scheduled dive operator. Access is by private expedition charter, research voyage or cruising yacht with Coral Sea experience, self-sufficient for several days and carrying compressor, oxygen and satellite communications. Flora Reef lies about 200 km east of Cairns, an overnight passage, and can be combined with Holmes Reef on an expedition itinerary.

There are no moorings; anchor in the lagoon in suitable conditions. Commercial tours need Parks Australia authorisation, and some islands are closed to landing.

These are remote oceanic reefs with no shelter from the south-east trades beyond their own reef rims, which blow 15–25 knots for much of April to October and make the multi-day open-ocean passage rough. Expeditions target calm windows, most often September to December; the lagoon anchorages give protection in moderate trades but the outer walls are dived only in light winds. December to April is cyclone season and trips are rarely scheduled then.

Currents on the walls and through passes can be strong; visibility is usually 30 m or more.

Dive the outer drop-off in calm conditions, following the wall with the current, and explore the lava-tube-like caves only with a torch, a guide and clear exits. Ascend under an SMB for tender pick-up.

No regular operator – occasional private expedition charters, research voyages and cruising yachts only; any commercial tour requires Parks Australia authorisation.