Papua is the largest and easternmost province of Indonesia, comprising most of Western New Guinea. Papua is bordered by the nation of Papua New Guinea to the east, and by West Papua province to the west. Its capital is Jayapura. It was formerly called Irian Jaya (and earlier West Irian or Irian Barat) and comprised all of Indonesian New Guinea.
A central east–west mountain range dominates the geography of the island of New Guinea, over 1,600 km (1,000 mi) in total length. The western section is around 600 km (400 mi) long and 100 km (60 mi) across. The province contains the highest mountains between the Himalayas and the Andes, rising up to 4,884 metres (16,024 ft) high, and ensuring a steady supply of rain from the tropical atmosphere. The tree line is around 4,000 metres (13,000 ft) elevation and the tallest peaks contain permanent equatorial glaciers, increasingly melting due to a changing climate. Various other smaller mountain ranges occur both north and west of the central ranges. Except in high elevations, most areas possess a hot humid climate throughout the year, with some seasonal variation associated with the northeast monsoon season.
The southern and northern lowlands stretch for hundreds of kilometres and include lowland rainforests, extensive wetlands, savanna grasslands, and expanses of mangrove forest. The southern lowlands are the site of Lorentz National Park, also a UNESCO World Heritage Site.
The province’s largest river is the Mamberamo located in the northern part of the province. The result is a large area of lakes and rivers known as the Lakes Plains region. The Baliem Valley, home of the Dani people, is a tableland 1,600 metres (5,200 ft) above sea level in the midst of the central mountain range. Puncak Jaya, also known by its Dutch colonial name, “Carstensz Pyramid”, is a limestone mountain peak 4,884 metres (16,024 ft) above sea level. It is the highest peak of Oceania.