Okains Bay is a settlement, beach and bay on the Banks Peninsula in the South Island of New Zealand.

It is located approximately 10 kilometres (6 mi) from the main town on the Banks Peninsula, Akaroa. It is 86km (90 minutes drive) from Christchurch. The sandy beach is popular with tourists and has a river estuary emptying into the bay. The settlement itself contains the Okains Bay Maori and Colonial Museum. There is a camp ground on the beach near the estuary. The beach is often deserted and there is a large cave to explore at one end.

Okains Bay is known as Kawatea in Māori. It is important to the Ngāi Tahu because a rangatira or chief called Moki established his Pa or settlement here when Ngāi Tahu migrated to Canterbury. Okains Bay has been recognised as the first landing place of Ngāi Tahu on Banks Peninsula. Carbon dating of artefacts suggest that Maori were present in Okains bay in the 1300s.

Okains Bay gained its European name from Captain Hamilton, who, when sailing past, was reading a book written by Okain (O'Kane), an Irish naturalist. It was first settled by Europeans around 1850. By September 1850 the first sections of land were sold by the Canterbury Association to the first European settlers. Due to the lack of roads, transport was to and from Lyttelton (21 miles away) by a steamer, which stopped along the way at Little Akaloa.

The main sawmill began operating in 1874. It is now a shearing shed. Timber was moved by a trolley line to the first wharf which was situated at the centre of the beach. The cheese factory opened in 1894 and closed in 1968.

Three different wharves were built at different times to accommodate boats berthing at Okains Bay. They were used for transporting livestock, meat, wool, timber, grass seed, dairy produce, store provisions and people. The first two wharves became inoperable due to the movement of the sand around them. The third wharf was closed and demolished in 1964 and the timber from it was used to repair road bridges in 1964.

Okains Bay is part of the Banks Peninsula Eastern Bays statistical area.

Banks Peninsula Eastern Bays statistical area covers 368.03 km (142.10 sq mi). It had an estimated population of 570 as of June 2024, with a population density of 1.5 people per km.

Historical population for Eastern Bays-Banks Peninsula

Year	Pop.	±% p.a.
2006	606	—
2013	654	+1.09%
2018	615	−1.22%
Source:

Before the 2023 census, the statistical area was called Eastern Bays-Banks Peninsula, with a larger boundary including Purau, covering 368.25 km (142.18 sq mi). Eastern Bays-Banks Peninsula had a population of 615 at the 2018 New Zealand census, a decrease of 39 people (−6.0%) since the 2013 census, and an increase of 9 people (1.5%) since the 2006 census. There were 258 households, comprising 306 males and 309 females, giving a sex ratio of 0.99 males per female. The median age was 50.7 years (compared with 37.4 years nationally), with 108 people (17.6%) aged under 15 years, 48 (7.8%) aged 15 to 29, 336 (54.6%) aged 30 to 64, and 123 (20.0%) aged 65 or older.

Ethnicities were 95.1% European/Pākehā, 12.2% Māori, 1.5% Pasifika, and 1.5% other ethnicities. People may identify with more than one ethnicity.

The percentage of people born overseas was 19.5, compared with 27.1% nationally.

Although some people chose not to answer the census's question about religious affiliation, 51.7% had no religion, 37.6% were Christian, 2.0% had Māori religious beliefs, 0.5% were Muslim, 0.5% were Buddhist and 1.5% had other religions.

Of those at least 15 years old, 141 (27.8%) people had a bachelor's or higher degree, and 60 (11.8%) people had no formal qualifications. The median income was $31,300, compared with $31,800 nationally. 93 people (18.3%) earned over $70,000 compared to 17.2% nationally. The employment status of those at least 15 was that 258 (50.9%) people were employed full-time, 117 (23.1%) were part-time, and 6 (1.2%) were unemployed.

Originally a cheese factory, the museum was developed thanks to the enthusiasm and collection of Murray Thacker, a local resident who spent his childhood collecting Māori taonga from local beaches. The collection includes tiki, fishing equipment, tools, weapons, cloaks and is of national significance.

The Tini Arapata marae was named by Aunty Jane Manahi for her mother, Tini Arapata Horau.

The original Okains Bay school building. This was built in 1872 and used until 1938.

The store and post office were built in 1873.

The Library was built in 1865.

The church was completed in June 1863. The total cost was 554 pounds, nine shillings and eight pence. It was built by a Mr. Morey, a stonemason. The stone and timber were all sourced locally and the slate roof and the stained glass were obtained from England.

In 1884 the organ was purchased from St Barnabas Church in Fendalton. The church bell was donated by the vicar in 1912. IN 1955, 400 pounds was spent repointing the stone work and other repairs. The floor began to crumble in 1959 due to dry rot. A concrete floor was laid.

The church was in 2020 the second oldest standing stone church in the diocese of Christchurch. It was severely damaged by the 2010 and 2011 Canterbury earthquakes.