The reefs around North Keeling Island are the least-dived in the Cocos group and among the least-dived anywhere in Australia. The island is a small, almost closed atoll 25 km north of the southern atoll, with a lagoon about 0.5 km² opening to the sea through a narrow channel on the east side, and since 1995 it has been protected as Pulu Keeling National Park, a Ramsar wetland of international importance. The park includes the surrounding waters, which are closed to fishing and accessible for recreational diving and snorkelling only by permit.

Underwater Australasia's account of a permitted expedition describes reef dives with visibility of over 40 m, abundant grey reef sharks, giant morays, trevally schools, parrotfish, surgeonfish, turtles, barracuda and dolphins, and healthy, vividly coloured coral. Because boats may not anchor except at designated landing points, all diving is done as drifts, and the currents running past this isolated island can be strong. The attraction is the sense of diving somewhere essentially untouched – a reef with no history of fishing, surrounded by open ocean and with a seabird colony overhead that includes perhaps the world's largest colony of red-footed boobies.

Divers who make the trip usually combine the reef dives with the SMS Emden wreck site on the island's reef. The practical reality is that such trips are very rare: Parks Australia currently limits landings to accompanied researchers and says no public tours operate, and weather cancels many planned crossings even in the doldrum season. Named individual dive sites around the island have not been published.

Anyone hoping to dive here should contact Parks Australia and Cocos Dive months ahead and treat it as a bonus rather than a certainty.

North Keeling Island (Pulu Keeling) lies about 25 km north of Horsburgh Island and the southern atoll – roughly a 1.5-hour boat ride across open ocean, depending on conditions. There is no regular public trip: Parks Australia currently limits landings to researchers accompanied by park staff and states that no public tours operate, while recreational diving or snorkelling in park waters requires a permit applied for through DCCEEW. Any visit must be arranged well in advance with Parks Australia (Cocos office on West Island) and a licensed local boat – historically Cocos Dive has run occasional permitted trips in the doldrum season.

Boats depart from West Island.

North Keeling sits in open ocean with no shelter, surrounded by a fringing reef with heavy surf. Parks Australia describes rough seas and a fringing reef that make getting ashore very difficult. The only realistic window is the doldrum season (November–April), and even then many planned trips are cancelled for wind or swell; during the south-east trades (April/May–October) crossings are generally not attempted.

The Emden lies in less than 8 m on the reef, where surge is the controlling factor – it can only be dived on flat days with minimal swell. Reef dives around the island can have strong currents and are run as drifts because anchoring is prohibited.

Drift dive: drop from the boat on the outer reef, descend to a comfortable depth on the slope and drift with the current along the reef, watching for sharks and schooling fish. Deploy a surface marker buoy before ascending for a live-boat pickup.

No regular operator. Access only by special arrangement with Parks Australia and a permitted boat; Cocos Dive has run occasional permitted trips in the doldrum season.