What is a characteristic shared by nearly all nations of Oceania?

Oceania is a vast region in the Pacific Ocean that includes Australia, New Zealand, and thousands of smaller islands. Because of its geography, most of the countries in Oceania are made up of islands or island groups, rather than large continental landmasses. For example, Fiji, Tonga, and the Solomon Islands are all island nations in Oceania. Papua New Guinea and Australia are considered both countries and continents, as they have significant landmasses as well as island territories.