An island nation or island country is a nation that is either composed of islands, or wholly situated on a single island. Most of the world's island nations are located either in the Caribbean or the Pacific. The largest island nation by both area and population is Indonesia. There are four sets of island nations that share borders: the Republic of Ireland and the United Kingdom, East Timor and Indonesia, Papua New Guinea and Indonesia, and Cuba and the Dominican Republic. Island nations typically have a stronger navy and coast guard, and oftentimes fishing is a major sector of their economies.