Diamond Harbour is a small settlement on Banks Peninsula in New Zealand.
It is on the peninsula's northern coast, on the southern shores of Lyttelton Harbour and is administratively part of the city of Christchurch.
The name is applied not only to Diamond Harbour proper but to the nearby settlements of Church Bay, Charteris Bay and Purau.
Diamond Harbour is the fastest growing community on Banks Peninsula. Its population and that of Charteris Bay and Purau grew from 879 in 1991 to 1,389 in 2006.
A ferry connects Diamond Harbour to Lyttelton, on the harbour's northern shore. In combination with buses from Lyttelton to downtown Christchurch, this allows residents of Diamond Bay to commute to the city.
Diamond Harbour supposedly received its name from the comparison of sunlight on the water to the shine of diamonds.