Sumner is a coastal seaside suburb of Christchurch, New Zealand and was surveyed and named in 1849 in honour of John Bird Sumner, the then newly appointed Archbishop of Canterbury and president of the Canterbury Association. Originally a separate borough, it was amalgamated with the city of Christchurch as communications improved and the economies of scale made small town boroughs uneconomic to operate.

John Bird Sumner, Archbishop of Canterbury, after whom the suburb is named
Sumner was surveyed in 1849 by Edward Jollie for Captain Joseph Thomas, the advanced agent of the Canterbury Association. His map showed 527 sections and numerous reserved and provisions for churches, schools, cemeteries, town hall, emigration barracks and other town amenities. However, his plans were abandoned through lack of funds and a new survey on which Sumner is based was carried out in 1860.
Captain Thomas named the settlement for Bishop John Bird Sumner, one of the leading members of the Canterbury Association. The Māori name for the area is Ohikaparuparu („o“ means place of; „hika“ means rubbing, kindling, or planting; „paruparu“ means dirt, deeply laden, or a preparation of fermented cockles).

Sumner is nestled in a coastal valley separated from the adjacent city suburbs by rugged volcanic hill ridges that end in cliffs that descend to the sea shore in places. Sumner Bay is the first bay on the northern side of Banks Peninsula and faces Pegasus Bay and the Pacific Ocean.

Because of its ocean exposure, a high surf can form in some swell conditions. The beach is gently sloping, with fine grey sand. It is a popular surf beach for these reasons.

Sand dunes have filled the river valley behind the beach. This has made housing construction relatively easy, although flooding at the head of the valley has been a problem in the past due to the reverse slope caused by the sand dunes filling the front of the valley. This has been addressed by a flood drain.

The rocky volcanic outcrop of Cave Rock dominates the beach. Until the mid-1860s, the feature was known as Cass Rock, after the surveyor Thomas Cass. There are other rocky outcrops in the area and the volcanic nature of the geology is readily apparent from several of the exposed cliffs around the valley.

A sea wall and wide esplanade have been built along the length of the beach to prevent coastal erosion.

Source: Wikipedia