Port Moresby is the capital of Papua New Guinea. Port Moresby is the capital and largest city of Papua New Guinea (PNG). The city is on the shores of the Gulf of Papua. Its population is around 300,000 and growing quickly. The indigenous people of the area are the Motu-Koitabu. Moresby, as it is commonly known, got its name from Captain John Moresby who arrived in 1873 as the first European visitor.