Flying Fish Cove is where almost every diver's Christmas Island trip starts, and many regard it as the finest shore dive in Australia. The cove is the island's only real harbour: a white-sand and coral-rubble beach backed by the old Settlement buildings, with the phosphate loading jetty and cantilever on its northern side. Underwater the layout is simple and typical of the island. A shallow fringing reef flat of hard coral runs out 30–50 m from the beach in 1–5 m of water, then the edge rolls over into a steep coral slope at around 9 m that becomes a near-vertical drop-off from about 18 m, plunging far beyond recreational depths – the island is the summit of an extinct volcano rising from more than 3000 m of water.

The coral cover on the slope is remarkably intact: plate and table Acropora, boulder Porites, lettuce corals, and sea fans and whips as you go deeper. Fish life is the draw. Christmas Island sits where Indian Ocean and Pacific faunas overlap, and the cove is the best place to see the island's endemic and hybrid reef fish – the Christmas Island (Cocos) angelfish, hybrid butterflyfish and angelfish crosses – alongside longnose, raccoon and pyramid butterflyfish, freckled hawkfish, squirrelfish, coral grouper, blue tang, surgeonfish, triggerfish and schools of fusiliers. Local accounts claim that most of the island's recorded reef-fish species can be found in the cove. Hawksbill and green turtles are common, spinner dolphins pass in deeper water, and in the wet season whale sharks cruise past the drop-off.

The cove contains two named sections that are often dived separately – Admin Wall, the steeper wall section, and the Sandpatch, a sandy garden-eel area used for training and night dives (see separate entries). Because it is shallow, sheltered for most of the year and needs no boat, it suits newly certified divers, training, photography, relaxed long dives and night dives, while experienced divers use it for afternoon dives after the morning boat trip. It is also a good snorkel at high tide over the inner reef. It is the one site on the island that can be dived fully independently with hired tanks.

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. Flying Fish Cove is the harbour at The Settlement, a two-minute drive from the dive shops and five minutes from most accommodation. Park in the beachside car park opposite the boat ramp at the western (southern) end of the cove, gear up at the car or picnic shelters, and walk straight down the concrete ramp into the water – a carry of only 20–30 m.

Alternatively step off the low water-level platform on the public jetty. Surface-swim or fin along the bottom 30–50 m over the inner reef flat to the drop-off. Tanks and weights can be hired from Extra Divers or Wet'n'Dry for independent dives.

Flying Fish Cove faces north-west and is the most protected water on the island through the south-east trade season (roughly April/May–November), when it is diveable almost every day. In the wet season (December–March/April) north-westerly monsoon swell, and swell from distant cyclones, rolls straight into the cove – the beach then becomes a surf break, the entry over the reef flat is dangerous and boat launching can be suspended; Extra Divers treat February–April as peak swell season. Avoid entering when waves are breaking on the reef flat; low tide makes the inner reef very shallow (snorkel it at high tide).

Tides are small (about 1 m). Visibility drops after heavy rain run-off and during red crab spawning (October–January), when crabs release eggs into the cove before dawn and whale sharks are most often seen off the drop-off. Night dives are best on calm dry-season nights.

Enter down the boat ramp, fin out to the drop-off following the reef, then turn left (west) along the wall and work down to about 18 m. Hold that depth on the slope/wall, watching the blue for pelagics, turn on half gas and come back shallower along the 9 m slope. Two chains running up the reef guide you back to the ramp like landing lights; do the safety stop over the reef flat at 5 m.

Extra Divers Christmas Island – guided shore dives, training, night dives and tank hire; CI Wet'n'Dry Adventures – shore dives, courses and tank hire. Both operators also use the cove for check dives and when swell closes other sites. Freedive Christmas Island runs freediving sessions here.