- Onotoa is a city located in the Nauru island, which is a small island nation in Micronesia, in the Central Pacific. It is the largest city in Nauru and serves as the country's capital. The city is situated on the southern coast of the island and has a population of approximately 6,800 people. Onotoa is known for its beautiful beaches, coral reefs, and natural beauty. The city is also home to important government institutions, commercial centers, and cultural attractions.