Ohаi is a town in the Southland Region of New Zealand's South Island, 65 kilometres northwest of Invercargill and 25 kilometres west of Winton. The 2001 New Zealand Census of Population and Dwellings gave its population as 399, a decline of 22.2% or 114 people since the 1996 census.
The literal meaning of Ohаi is unclear, but a mural in the town centre reads "OHAI" and then curved underneath "Place of the Stone". The name Ohai was recorded by James Herries Beattie as in use for the area before 1840. Up until as late as 1958 Morley stream near the town was officially called Ohai Stream in the Wairio District Survey maps. It is likely that the area was originally named in relation to an historic Maori stone quarry that is nearby as described in New Zealand Archaeological Association Schedule & Maps of Recorded Archaeological Sites, Map 7, Page 271
Ohai township was founded in 1917 following the discovery of large amounts of high quality coal in the area. However, the early days of mining were restricted by poor roads. Coal production boomed in the area in 1925, when the Ohai Railway Board opened a new line linking Wairio to the Ohai Railway District. This line also carried workers between Wairio and Ohai on a passenger steam train called the ‘Piecart’.
In order to provide convenient transport of the coal to markets beyond the local area, a privately owned railway extension from the New Zealand Railways Department's Wairio Branch was opened by the Ohai Railway Board in January 1925. In 1934, this line was further extended beyond Ohai to Birchwood, but the terminus had reverted to Ohai by the time the line was incorporated into the national rail network in 1990. The line is now called the Ohai Line and is one of the very few survivors of a formerly extensive rural branch line network. The Ohai Railway Board Heritage Trust, which had no connection with the Ohai Railway Board, was involved in the restoration of steam locomotives including members of the P and V classes and a railway museum was been established, but the trust has been dissolved.
Mechanization of mining methods in the 1980s brought huge changes to Ohai (and the nearby sister town of Nightcaps). Many families with generations associated in mining left the area. In Ohai today, shearing now rivals mining as the biggest industry employer in the town. Recent times have seen a number of people move into the Ohai/Nightcaps area (many of them North Islanders), attracted by the rural lifestyle and affordable housing. Ohai's rural location lends itself well to many outdoor pursuits. These include fishing and duck hunting, the close proximity of rivers and duck ponds making these popular local pursuits.
Ohai is the terminus of New Zealand State Highway 96, which runs from Mataura via Hedgehope and Winton. The primary school closed in 2003 and students now attend school in nearby Nightcaps. A heated and covered swimming pool, tennis courts, golf course, a bowls club, a police station, and a recreational reserve are located in the town.
The Takitimu District Pool is a large (33 metre) heated, covered pool in Ohai. It is open for use during daylight hours from around late October through to March. Sliding doors allow the pool area to be opened out to an outdoor garden. Public sessions are available at certain times most afternoons during the season. Once a week during these sessions the 'inflatable' is used in the pool. Alternatively, family or single keys can be purchased seasonally, providing users with unlimited use during daylight hours. Local coal, supplied by Solid Energy, heats the swimming pool. Many volunteers donate their time to help maintain and manage this facility.
Despite concerns about the closure of the mine, many residents look forward to the establishment of recreational lakes that will be connected to the local trout stream, and the construction of walkway around the Morley streams and proposed lakes. An example of the coal mine rehabilitation with the similar community use concept can be found at Glyncorrwg South Wales United Kingdom. 
Major petroleum company L&M Energy is successfully completing the final stages of its well-drilling programme for coal seam gas production on the outskirts of the town. If the Ohai coal seam gas project is able to convert its existing 3P gas reserves into 2P reserves for development it could be the biggest onshore gas project in New Zealand, creating growth and opportunities in this town.
Coal is to be mined again on a small scale, commencing mid-2012.
Threat of Mine Subsidence
During 2012 there was some concern from some residents of a possible mine subsidence risk in Ohai, due to several old mining tunnels under the Northern part of the township dating from pre-World War II, the old Wairaki 3 mine works.
In July, a man had called the council claiming his drainage system was affected by subsidence, but an engineer had concluded it was not the case. Solid Energy had told the council the risk of subsidence from the old Wairaki 3 mine works, which lie under the northern side of the township, was "very minimal", he said, since subsidence normally occurred in the first few years, but they would continue working together to examine it.
After an unrelated survey of 2km of pipes was completed, Council Chief executive Dave Adamson said overall, the survey work did not highlight any areas that may cause significant immediate concern. "Now that we have some good information on the condition of the pipes it will allow us to plan better for the long term. It needs to be made clear the purpose of the survey was to determine the condition and remaining life of the pipes, it was not to prove or disprove the existence of a subsidence issue or problem." "However, any subsidence would have been obvious during the camera survey", Mr Adamson said.
Ohai CDA chairman John Hogg said he had not heard of houses or gardens subsiding in the township. Council chief executive Dave Adamson said he had asked staff to look at the problem, but many old mining towns in New Zealand had tunnels underneath them. "As far as I know we haven't had any direct reports of subsidence issues to date," he said. However, going public with the potential subsidence issue was not welcomed by some in Ohai. One of the CDA members who resigned, said he was unhappy another CDA member had gone to the Southland Times,(Regional Newspaper). 
- Quickstats about Ohai
- "Ohai Community Profile(published)". .stats.govt.nz. 2003-05-30. Retrieved 2012-09-19.
- "GLOBAL - Full Display - Record 1 of 1". Tapuhi.natlib.govt.nz. Retrieved 2012-09-19.
- "wairio survey district 1958 | Items | National Library of New Zealand - National Library of New Zealand". Beta.natlib.govt.nz. Retrieved 2012-09-19.
- "Ohai". Western Southland. Retrieved 2012-09-19.
- "Takitimu District Pool". Western Southland. Retrieved 2012-09-19.
- "Solid Energy confirms Ohai Mine closure | Scoop News". Scoop.co.nz. 2009-02-19. Retrieved 2012-09-19.