Papua New Guinea (Tok Pisin: Papua Niugini), officially the Independent State of Papua New Guinea, is a country in Oceania, occupying the island of New Guinea and numerous offshore islands. It is located in the southwestern Pacific Ocean, in a region defined since the early 19th century as Melanesia. Its capital, and its biggest city, is Port Moresby. It is one of the most diverse countries on Earth, with over 850 indigenous languages and at least as many traditional societies, out of a population of just under 8 million. The country is also one of the world's least explored, culturally and geographically, and many undiscovered species of plants and animals are thought to exist in the interior of Papua New Guinea.