The first European trading vessel is believed to have worked Oamaru's open roadstead in 1854. At that time there was no township, merely a sheep station. The coast was desolate and rough:
To the right was the bare hump of Cape Wanbrow, with the sea dashing against the rocks at its foot, for there was then no intervening shelf of flat land. On the left, the low hills were broken by a deep gully before turning north in a long, even wall which edged gradually further from the sea as it marched northwards. Between this rampart and the shore was a narrow strip of plain stretching north to a flat horizon and broken off abruptly at the sea-edge.
The sheep station, and the growing number of settlers loaded and unloaded their cargoes in the surf, with Moeraki Maori playing a prominent part in the difficult, dangerous work. By the late 1850s Oamaru had gained a landing service, with the Provincial Government providing a derrick for hoisting goods from the top of the bank near the landing. A goods store was built and the Maori workers accommodated in whare on the beach. Service was slow and expensive, but allowed Oamaru to develop into a small settlement. It would boom from the early 1860s as a goldfields servicing centre and a supply town for a prosperous wool and grain growing region.
The town's coastline was very exposed. Cape Wanbrow offered some protection from southerly storms but the beach was open to northerlies and very dangerous. Many North Otago residents questioned the sense of using the place, but it was declared a port of entry in 1861. By 1863 there were both inner and outer moorings available, but it was still a dangerous site for ships and insurance firms refused to cover ships anchoring at Oamaru at the normal rate. The foundation stone of Oamaru's first jetty was laid in December 1865 and in 1867 an L-shaped jetty had been completed in the lee of Cape Wanbrow but it was too exposed to be satisfactory. That jetty was destroyed in February 1868, when a deep storm also wrecked two overseas wool ships, the Star of Tasmania and Water Nymph and the coaster Otago. Later that month Oamaru residents observed a day of humiliation and fasting, something the Oamaru Times considered less useful than a collection.
The disaster of February 1868 forced provincial authorities to re-examine their plans and the Oamaru Dock Trust was established in 1869, and active until 1874. The grant to the Dock Trust was for the "improvement of the Harbour of Oamaru and the construction and maintenance of such Dock's piers and other Works thereon as may be deemed advisable" by the superintendent of Otago "for facilitating the trade and commerce of the said Town and Port of Oamaru." The initial plan was for an enclosed dock in the lagoon of the Oamaru Creek (which then took a more meandering route to the sea) but this was amended to a deepwater breakwater port instead, following plans drawn up by Scottish harbour engineer John McGregor in 1871. These plans included the construction of a breakwater near the site of the original jetty, under Cape Wanbrow and a mole on the northern side to form a smooth water basin. Work began on the breakwater in 1871 and progressed slowly. In 1874 the Oamaru Harbour Board replaced the old Dock Trust and later that year a statute vested 171 acres of land in the Board. This consisted mostly of the bay itself but included a strip of land covering the harbour railway. The land originally granted to the Dock Trust includes the land between the what is now the east side of Tyne Street and the sea. This block is a major part of the Harbour/ Tyne Street Historic Area, where the buildings are linked to the Port functions, particularly the warehouses.
The port's safety improved long before the breakwater was completed. In 1875 the first wharf, a concrete structure alongside the breakwater, was opened in 1875. Macandrew Wharf, as the 50-metre wharf was known, was opened on 6 May. By 1876 the wharf was 110 metres long, offering two berths and an average depth alongside of four to five metres.
More wharves followed. Normanby Wharf, another concrete wharf, offering berthage on three sides, was finished in 1878 and the Cross Wharf, a short concrete breastwork wharf located between Normanby and Macandrew, was ready by 1879. Normanby could handle ships of 2 000 tons. By the end of 1879 the 380 metres of berth age could accommodate six to seven vessels, enabling the boating service to be discontinued.
It was the discovery, however, by board secretary Thomas Forrester (1838-1907) in 1878 that the seabed was merely compacted shell and sand and not rock that was the making of the Port of Oamaru. This spurred a major expansion programme in 1883, centred around the purchase of a steam dredge, the Progress, and the construction of an export pier, Sumpter Wharf. By the end of 1884 Oamaru had stolen a march over rivals such as Otago and Timaru. Sumpter Wharf offered a depth of seven metres and the Elderslie, the first steamer for the New Zealand-United Kingdom meat trade, was visiting the town; that vessel was intended to trade exclusively between Oamaru and London.
The Oamaru Harbour Board completed the breakwater early in 1884, when Miller & Smilie placed the last 300-tonne monolith in place. The final structure was 564 metres long, 11 metres wide and 9.8 metres high. About the same time the 493 metre-long rock mole was complete to the north.
By then the board had over-reached itself financially. Storm damage to the breakwater in 1886 merely compounded its financial problems as it struggled to service interest payments. In 1894 it went into receivership, three years after defaulting on interest payments.
Like most ports, Oamaru's business rose and fell according to the health of the economy. From the 1890s the port's traffic increased and in 1907 the board, still in receivership, opened its largest wharf, Holmes Wharf, on the mole. This kept Oamaru in the export trade and in 1909 the board's loans were consolidated and the receiver was stood down.
In 1913 Oamaru Harbour was secretly visited by the Terra Nova, Captain Robert Falcon Scott's ship, bearing news of the death of Scott and his companions during their expedition to reach the South Pole. Contemporary newspaper reports said that the Terra Nova arrived in Oamaru around 2 am on Monday 10 February. She was warned off by the night watchman and responded by signalling she was sending a boat ashore. The boat was directed to Sumpter Wharf and two of the four men landed, Lieutenant Penn ell and Mr Atkinson. They would not inform the night watchman which ship they were from but instead contacted the harbourmaster, Captain Ramsay, from the night watchman's office. Ramsay put up the officers overnight, after which they caught the train to Christchurch, having telegraphed news of Scott's death from Oamaru. As K. C. McDonald wrote, this event caused 'the name of Oamaru to be read if not remembered throughout the world'.
There was a short recession in 1921 but in general the interwar period was a good one for the port, which was visited by larger ships (the Onawa and Ontario, each of about 10,100 tons, called in the late 1930s). In 1928 Holmes Wharf was lengthened to accommodate these ships. In 1936 the Harbour Board began its final big construction programme, an extension to the breakwater. The Ramsay Extension (as it was named), was angled out to provide sheltered water for a dredged channel out to deeper water. But the work, which depended on subsidised relief labour, proceeded slowly and was 'capped' in December 1944, short of even its revised target length; in any case, the last UK trade freighter had called in 1940. Gradually the extension broke up.
During World War II a battery was constructed on Cape Wanbrow to protect the harbour from enemy attack. After the Japanese attack on Pearl Harbour in December 1941, New Zealand made a concerted effort to provide defences for its secondary ports, as well as the major ones. The battery at Cape Wanbrow consisted of a camp for the service personnel, a gun emplacement which housed a former United States Navy 5-inch gun, a magazine and a battery observation post. A machine gun pit, located further south along the coast, provided protection for the battery from any attack from the south. The gun was never fired at enemy ships and was removed to Burnham Military Camp in 1945. The camp huts and mess/kitchen were also removed from the site.
Despite the loss of overseas shipping, the port's trade generally increased in the late 1950s and the early 1960s before coastal shipping began to lose trade share to rail and road transport. At the beginning of 1966 the Customs Department closed its Oamaru office and Oamaru Harbour ceased to be a port of entry. In 1970-1971 Oamaru was used by overseas ships servicing the Sedco oil rig off the coast. In 1973-1974 a few small Tongan ships also called to load frozen meat, but these did not developed into sustainable business. In 1973 the last trans-Tasman ship, the Koraki, called. In 1974 the last coaster, the Holmdale, took away the last cargo. In 1975 the Chair of Board announced that no cargo-moving vessels had entered the port in the last 12 months and therefore Oamaru had ceased to function as a port.
The Harbour Board celebrated its centenary in 1974 but four years later it would be abolished and replaced by a Harbour Committee made up of representatives from the local borough councils. Within a few years New Zealand Cement Holdings was planning to re-open the port. It received the necessary approvals from the New Zealand Ports Authority and sketches called for the construction of a 10,000-tonne capacity silo behind Friendly Bay, a loading berth on Holmes Wharf and the demolition of Sumpter Wharf to improve the swinging basin, but the investment was never made.
Since then the harbour has served a handful of inshore fishing vessels and recreational craft. The oil industry's tanks and pipelines have been removed and the harbour has become more of a tourist-oriented place. In the 1990s a blue penguin-viewing colony was established near the end of the breakwater and artisans and steam train enthusiasts have a base here too.
Oamaru Harbour has also always been used for recreational activities. The first regatta was held on 25 May 1885 to celebrate the 66th birthday of Queen Victoria and included both sailing and rowing races. It proved to be very popular, with music from the Oamaru Garrison Band. A further regatta was held in 1910 and between then and 1947 other regattas were occasionally held. The harbour also proved suitable for rowing. In 1895 the Union Rowing Club erected a landing stage to enable boats to be launched more easily (as the reclamation meant the sloping shingle was disappearing. (OM 23/12/1895)The Oamaru Boating Club was established in 1919. Friendly Bay, the small sandy beach created in the northwest corner of the harbour became Oamaru's beach with circuses playing on the foreshore from the 1890s and annual carnivals held between Christmas and New Year's from the 1920s. Fishing off the wharves was also popular as was at one time trolling for flounder. The local Beautifying Society, formed in 1908, (such societies a feature of late nineteenth/early twentieth century New Zealand society) approached the Harbour Board in 1912, asking for assistance to create a picnic and beach area. The Society was proposing to roof in the old concrete mixing shed and also to install a fireplace and seating in the old quarry area.
Until the 1970s Oamaru Harbour was one of the country's major seaports. Its heyday was the late 1870s and early 1880s when trade flourished. With the economic depression of the 1880s, and the development of rail links and more sophisticated port facilities in Dunedin and Timaru trade from the Oamaru slowly declined. This decline has contributed to the character of both the harbour and the town, creating aspects of townscape and harbourscape relatively untouched by more modern developments. As Gavin MacLean has noted its story is one of struggle and not without controversy. It was a facility fought for and valued by its community, through financial difficulties, economic depression as well as calmer times. The success of the port made an enormous contribution to the development of the province, providing an export port for the grain, wool and meat which made up a substantial part of the export trade from Oamaru. The character of Oamaru, particularly the commercial area next to the harbour, is founded on the Port - the grain stores, harbour board office, the, merchants, customs building and banks - all these surviving historic buildings represent an economic vitality provided by the Port of Oamaru which shaped the town itself.