Submarine Rock is named for the shape of its central reef, which resembles a submarine lying on the slope. Extra Divers describe a gradual slope from 10 m to 20 m, often dived as a current-assisted drift that combines relaxation with excitement; Diveplanit and Divernet describe the outer wall, where the drop-off reaches 50 m, with big healthy boulder corals, fans along the wall, and crevices and overhangs to explore.

The dive has two personalities. The upper section is a sloping reef of boulder and plate corals that makes for easy cruising, with butterflyfish, angelfish, triggerfish, surgeonfish and anthias, while the drop-off gives the feeling of hanging over deep water. Fans and whips grow along the wall and in the overhangs, and crevices shelter groupers, squirrelfish and moray eels. The current that often runs along this part of the coast brings in pelagics: manta rays, eagle rays and grey reef sharks cruising by, according to the Diveplanit write-up, and the chance of whale sharks during the wet season.

Operators frequently run Submarine Rock and Leanne's Leap as one continuous drift, starting on the rock and letting the current carry the group west along the drop-off until it gives way to the coral garden at Leanne's Leap. The boat follows the divers' bubbles and picks them up at the end.

It suits intermediate divers comfortable with a moderate drift, depth control on a wall and deploying a DSMB. Less experienced divers can enjoy it by staying on the upper slope with the guide.

Fly from Perth (about 4 hours, two to three flights a week, some via Cocos Islands) and hire a car – there is no public transport. Both dive centres are in The Settlement and launch their boats from the jetty/boat ramp at Flying Fish Cove, normally at about 8 am for a two-dive morning trip. From the cove the boat runs west past Smith Point and south-west along the north coast (the 'dog's back') along the coast for roughly about 25 minutes to Submarine Rock.

There is no land access to the dive, and the vertical sea cliffs mean no exit other than the boat. Operators choose sites on the morning according to swell and wind.

On the north coast, which is in the lee of the south-east trade winds from roughly April/May to November – that is the calm, reliable season here with glassy seas and 30 m+ visibility. From about December to March/April the north-west monsoon brings northerly and north-westerly swell (and occasional cyclone-generated swell) that can make the north coast undiveable and the Flying Fish Cove ramp unusable for days; Extra Divers treat February–April as peak swell season when trips are often cancelled. Any swell over about 1.5 m from the north-west quarter usually cancels the site.

Visibility dips after heavy rain run-off from the plateau and during red crab spawning (Oct–Jan) when plankton blooms. Tides are small (about 1 m) and rarely matter, but currents along the coast can pick up without warning.

Descend on the 'submarine' rock at 10–12 m, then drift along the slope and wall with the current at 15–25 m, looking into crevices and overhangs and out to the blue for mantas and sharks. Continue one-way towards Leanne's Leap as the reef shallows into coral garden and do the safety stop there under a DSMB.

Extra Divers Christmas Island – regular drift dive, often combined one-way with Leanne's Leap; CI Wet'n'Dry Adventures – dived on the run west.