Port Moresby Coast

Papua New Guinea has 5,152 kilometres of coastline spread across the PNG mainland and the island provinces, facing the Coral Sea to the south, the Solomon Sea to the southeast, and the Bismarck Sea to the north. The tidal regime varies by geography: at Port Moresby on the Coral Sea, spring range is approximately 2.0 m, semidiurnal; at Madang on the Bismarck Sea north coast, the range decreases to around 1.3 m; at Kimbe on West New Britain, range is 1.2–1.5 m. All three are mixed semidiurnal with two daily tidal cycles of unequal height. Port Moresby sits at the head of two natural harbours — Fairfax Harbour (the inner port) and Walter Bay to the east — on a peninsula of raised coral limestone. The city of roughly 400,000 is the largest in the Pacific island region outside Australia and New Zealand. The harbour approaches are bounded by the Papuan Barrier Reef, one of the longest fringing reef systems in the world, which runs 400 kilometres along PNG's southern coast and shelters the coastal waters from the full Coral Sea swell. The reefs inside and along the Papuan Barrier Reef are among the most extensive and least dived major reef systems in the world: PNG's topography, infrastructure challenges, and political-security perception have collectively kept recreational diving pressure low. Madang, on the Bismarck Sea north coast, is the country's premier dive destination by infrastructure and reputation. The Madang Lagoon is enclosed by a barrier reef with five navigable passes; the interior reef system, particularly around the offshore islands of Kranket, Siar, and Wongat, carries exceptional soft-coral diversity and visibility that regularly exceeds 30 m. Kimbe Bay on West New Britain is recognised in the marine biology literature as having the highest coral and fish species density of any bay in the Pacific — a claim based on systematic scientific surveys and not promotional language. Over 860 coral species and 1,000 fish species have been recorded in the bay. The palm oil industry that dominates the West New Britain coast has not, to date, significantly degraded the bay itself.