Indonesia–Papua New Guinea border
The Indonesia–Papua New Guinea border separates the Papua, Highland Papua, and South Papua provinces of Indonesia from the Sandaun and Western provinces of Papua New Guinea. The border, which divides the island of New Guinea in half, consists of two straight north–south lines connected by a short section running along the Fly River, totalling 824 km (512 mi).
Source: Wikipedia — Indonesia–Papua New Guinea border (CC BY-SA 4.0)