The coast here is fringed with rocks. The area is completely open to all but E to S winds. In SE to S winds the southern end of Oamaru Bay gives good holding and shelter in about 16 metres of water. This can be a satisfactory place to wait for southerly winds to ease before crossing Cook Strait.
Motungarara Island and The Twins are fringed with rocks and seaweed. The eastern end of Motungarara has two reefs extending 200 metres form the south-eastern end with weed and sunken rocks.
One reef extends to the north-east and the other to the south-east. Weed banks also extend 50 metres from the western end. There is a deep clear passage between The Twins and Motungarara.
One can anchor safely overnight here if experienced. Onehunga bay can be quite shallow.