The harbour has three main arms. The Mangere Inlet at the northeast lies close to Auckland's central city area, with the inner suburbs of Onehunga and Te Papapa situated close to its northern shore. The Otahuhu and Mangere urban areas lie south of this arm, which is crossed by the Mangere Bridge. In the southeast is the Papakura Channel, which extends into the urban area of Papakura. In the southwest a further inlet known as the Waiuku River reaches south to the town of Waiuku. The harbour reaches into Mangere Lagoon, which occupies a volcanic crater. Auckland Airport is located close to the harbour's eastern shore.