What is the terrain and geography like in Papua New Guinea?
The main island comprises 85% of Papua New Guinea’s total land area. A complex system of mountains extends from the eastern end of the islands to the western boundary with the Indonesian province of Papua. Precipitous slopes, knife‑sharp ridges, great outcroppings of mountains rising to heights of almost 15,000 feet, and broad upland valleys at altitudes of 5,000–10,000 feet characterize this area. Most of the terrain is covered by dense jungles of tropical rain forest. Large rivers forming the world’s twelfth largest riverine network flow to the south, north and east; few are navigable except by small boats in the lower reaches. The largest river, the Fly, which begins in the mountains of western Papua, flows over 700 miles, and can be navigated for 500 miles.
Between the northern and the central range of mountains lies the Central Depression, which contains the Sepik, Ramu, and Markham River valleys. Lowlands and rolling foothills of varying widths stretch along most of the coasts. Huge tracts of wetlands are common in the poorly‑drained coastal areas. On the southwest littoral, the great delta plain of the Daru coast forms one of the world’s most extensive swamps, exceeding 100,000 square miles.
The archipelagic areas of Papua New Guinea include three major islands—New Britain, New Ireland, and Bougainville—as well as a great variety of smaller, often very isolated island groups. The islands contain many volcanoes, both active and dormant; rich agricultural zones; and considerable mineral wealth. Thousands of coral reefs make the surrounding waters a mecca for marine biologists and scuba divers, while several of the smaller island groups, including the Trobriands and Manus Island, were the sites of classic anthropological studies.
Although tropical, temperatures are not extreme. Most lowland, coastal, and island areas have a daily average temperature of 81°F, and seasonal variations are slight. In the highlands, temperature varies with altitude. At 6,000 feet, the average temperature is 61°F; daytime temperatures rise to 90°F and nighttime temperatures fall between 40°F and 50°F. Lowland humidity is uniformly about 80% with very little seasonal variation. Humidity fluctuates more in the highlands where temperatures are lower.