Cabbage Patch is the dive most people associate with Cocos, and it earns the reputation. The site is a hillside almost entirely covered by one type of coral – the green-and-gold, leafy cabbage coral (Turbinaria) – growing in overlapping whorls that together form a single colony-scape 6–20 m across. The official tourism listing gives the depth range as 6–27 m; most of the interest is between 6 and 20 m, where the coral is thickest and the light strongest.

On a sunny day with the typical 25 m-plus visibility the whole slope glows gold, and the effect is best seen by hanging off the reef a few metres and looking back at it rather than nosing into individual plates. The coral is home to clouds of small fish: anthias and chromis hover in their thousands just above the whorls and duck into them as divers pass, and the scale of these schools is what makes the site photogenic. Around the sandy margins at the base of the slope, spotted garden eels rise out of the sand in colonies and retreat as you approach, and whitetip reef sharks are commonly found resting on the sand or under coral overhangs.

The dive is gentle: a shallow, mostly sheltered reef on the north-western side of the atoll, close to West Island, with usually mild current. That makes it a common first dive of a Cocos trip and a good check-out site for divers who have not been underwater for a while, but experienced photographers return to it repeatedly for the wide-angle opportunities. Monoculture coral fields of this scale are unusual anywhere, and the reef's condition reflects the remoteness of Cocos – the islands have no run-off from agriculture or rivers, very little fishing pressure and very few divers, and the official tourism site describes the reefs as among the healthiest in Australia.

Because the corals are brittle and dense, good buoyancy matters: fins kicked into the slope break plates that take years to regrow. Cabbage Patch sits close to Rose Wall and Ski Run, and the three sites are often combined across a morning's diving or used interchangeably depending on the tide. It suits every level of certified diver and is a standout snorkel on calm days over the shallowest part of the field.

Fly to West Island on the twice-weekly Virgin Australia service from Perth (usually routed via Christmas Island; allow 7–10 days on the islands to absorb weather and flight delays). Cocos Dive collects divers from West Island accommodation in the morning (pickup around 8 am, departure about 9 am) and runs its boats from West Island into the lagoon. The north-western sites around Horsburgh Island are among the closest to West Island: the boat runs north up the inside of the lagoon past the northern tip of West Island towards Horsburgh, a short, usually sheltered ride.

Moorings or live-boat drops are used; there is no shore access. The lunchtime surface interval is normally taken on the beach at Direction Island before the second dive.

Cocos has two seasons. The south-east trades blow steadily from roughly April/May to October, often 15–25 knots, which chops up the lagoon and pushes swell onto the eastern and southern outer reefs; divers are then kept to sheltered sites. The doldrum season (November to March/April) brings lighter, variable winds, flatter seas and the widest choice of outer-reef sites, and is the best time to dive, though it is also the tropical cyclone season and squalls pass through.

The north-western rim sits in the lee of the atoll during south-east trade winds, so these sites are often the ones that stay diveable when the trades blow; a strong westerly or north-westerly swell (uncommon, mostly in the doldrum season or with passing cyclones) closes them. Tidal flow through the Western Boat Passage near Horsburgh sets up currents along the reef edge, so dives are timed with the tide; visibility is best on the incoming tide when clear oceanic water pushes in.

Drop onto the top of the coral field at 6–8 m and drift slowly down the slope through the cabbage coral to 15–20 m, looking over the sand margins for garden eels and resting whitetips. Hold the mid-slope for most of the dive, then work back up across the shallower cabbage coral into sunlight for a long shallow finish and a safety stop over the reef top.

Cocos Dive (Dieter Gerhard, West Island, operating since 1990) is the only scuba operator on the islands and the only way to dive this site. It runs seasonal two-dive day trips with lunch and a surface interval on Direction Island, maximum 10 divers per trip; sites are chosen on the day according to wind, tide and diver experience. Trips book out well ahead and courses are currently suspended, so arrive certified.