nauru, ( ) officially the republic of nauru, is a sovereign island nation located in the micronesian south pacific. its nearest neighbour is banaba island in the republic of kiribati, due east. nauru is the world's smallest island nation, covering just , the smallest independent republic, and the only republican state in the world without an official capital. with 10,670 residents, it is the third least-populated country after vatican city and tuvalu.