Two Ridges is named for its main feature: two coral outcrops that the official Cocos tourism listing likens to 'a sunken, upside-down catamaran hull'. The depth range is 14–25 m. The two ridges run side by side with a channel between them, and the dive naturally follows that shape – down the gully between the hulls, around the end of one ridge and back along the outside.

The ridges are covered in hard coral and support the usual variety of Cocos reef fish, with the sides of the ridges falling to sand. The site sits beside Cannons, Fan Wall and Cable Bommie on the northern rim near Direction Island, and shares their reputation for large animals. The official listing notes it as a favourite of Kat, the resident male dugong that for years frequented this part of the atoll, and manta rays are regularly seen here; the northern rim near Direction Island is the area where Cocos' reef manta population is most often encountered, whether at cleaning stations or feeding along the rim.

Beyond the big animals, it is a moderate, easy-to-navigate dive with good coral and simple topography, and a sensible choice for Open Water divers. The shape also makes it a good site for photographers, who can use the ridges to frame a manta or a school of fish against the blue. Visibility is usually 20 m or better, best on the incoming tide.

Public documentation is thin beyond the official listing, so detail on specific features along the ridges is best obtained from the guide on the day. Divers who see a manta or dugong should stay low, keep still and let the animal approach rather than chasing it.

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. These sites lie along the northern rim of the atoll near Direction Island, at the north-eastern side of the lagoon around Port Refuge.

The boat crosses the lagoon from West Island to reach them, and they are conveniently paired with the lunchtime surface interval on the beach at Direction Island (eco toilets and shelters, no shops). Live-boat drops or moorings; no shore access.

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 northern-rim sites near Direction Island catch tidal flow through the passage at Port Refuge; the incoming tide brings clear ocean water and upwelling along the drop-off, the outgoing tide carries lagoon water out and lowers visibility. In strong south-east trades the lagoon crossing is choppy and wet but these sites are partly protected by the atoll; big northerly swell, uncommon, closes them.

Descend between the two ridges at about 15 m, swim along the gully between them, then loop around one ridge and back along the other, checking the sides and the sand for life. Watch the blue and the sand for manta rays and dugong. Ascend at the shallow end of the ridges for the safety stop.

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.