Days Bay is a residential area in Lower Hutt in the Wellington Region of the North Island of New Zealand. It is walled on three sides by steep bush-clad slopes. Most of its level land is occupied by Williams Park and an independent boys' primary school, originally a part of Williams Park. Wellington shipowner, J H Williams, bought land in Days Bay near the end of the 19th century to create custom for his smaller vessels, building a wharf and turning the bay into a sports and resort development for day-trippers and holiday-makers. Williams sold his interest in 1905 and the new owners split off building sites on unneeded land. The Eastbourne Borough Council bought the ferries in 1913 and the accommodation, Days Bay House, was sold to Wellington's Croydon School. The following year the Wellington City Council with central government support and public subscription bought the resort for the benefit of the public though without its accommodation and, in view of the large cash contribution by the founder's mother, named it Williams Park.

Days Bay's ornate wooden late-Victorian Pavilion, providing teas on its deep verandahs, a restaurant, evening dances and outdoor concerts was very popular until it was totally destroyed by an early Sunday morning fire in October 1952. It was eventually replaced by a small building. Better road access was achieved, a bus service provided and the ferries lost custom and Williams Park lost some of its visitors. Suburban electric trains up the west coast and the rise of private cars in the second half of the 20th century opened new options for Wellingtonians.

Since public ownership in 1914, aside from the maturing of trees, no waterslide and a new small pavilion, more than a century has elapsed and Williams Park has changed little.

The original Māori name for Days Bay was Otuamotoro. This was a Ngati Ira fortified village "built by Te Hiha six generations ago" (as of 1865).

Days Bay was at first known to settlers as Hawtrey Bay. It was settled by George Day and his family who had immigrated from Kent aboard the Arab in 1841. A William Tod appears to have employed George Day to look after his interests in the area while he went south. They had permission to cut and sell firewood and timber. The Days built their house in the bay and operated a schooner that ferried early settlers between the Hutt Valley and Wellington. After their house was severely damaged by an earthquake in November 1849 the Day family left the bay aboard the schooner Flirt, captained by their eldest son George Frederick Day, and sailed to Lyttelton in Canterbury, the port for the new settlement of Christchurch. By December 1849 the family had settled in Sumner and George Day had become a road construction overseer, while the rest of the family appears to have continued their firewood, timber and shipping activities.

A destination resort is a self-contained development that provides for visitor-oriented accommodations and developed recreational facilities in a setting with high natural amenities.

J H Williams a Wellington ship owner and son of another prosperous Wellington ship owner like some other owners ran excursions to Lowry Bay in a work boat dressed for the day in flags and bunting. They were popular with church groups, employees out for their annual company picnic and the like as well as the general public. Lowry Bay's wharf was becoming unsound and at the end of the 1880s Williams rebuilt it at his own expense. A refreshment booth was organised, playground equipment was brought in for young children and races and other activities set up for the older ones and the excursions became a great success. Williams' income came from carrying the people to Lowry Bay and not from their activities once on dry land. Wanting to participate in the takings from those shore activities he took an opportunity in November 1894 to buy the principal 125 acres section of beachfront in Days Bay, got permission to build a wharf and had the rest of the Bay surveyed. Twelve months later his wharf was finished though he ran his first excursion there the month before on 9 October 1895.

In November 1896 the Evening Post reported steamers Duco and Mana were unable to take all who wished to go to Day's Bay. The following winter Williams bought a further 700 acres of land by York Bay and Day's Bay including 200 acres in Portuguese Joe Bay. Days Bay (the prettiest spot in the harbour) was always ready for business and rapidly proved so popular the Chief Post Office by Queens Wharf undertook to a fly a flag to signal there would be no postponement of the day's harbour trip. Large wharf gates—since removed—had to be put up at Days Bay to control the crowds as well as barricades and at the city end the Wellington Harbour Board felt obliged to build a special Ferry Wharf—finished by autumn 1897—otherwise the swarms of trippers created real difficulties at their Queens Wharf. Newspaper reports of as many as six shark fins at once in the warmer waters of the eastern harbour and infestations of venomous katipō spiders in rotten wood on Day's Bay's high tide mark did not deter them. Donkey rides were there on the beach by 1901.

These excursions were not on a regular schedule but fitted between the everyday commitments of Williams’ vessels. Generally passengers were carried by Duco which also performed tugboat duties but at the end of 1897 the specially designed and built for Williams, licensed for 1,029 passengers, electrically lit steamer Duchess arrived from her builders in Glasgow. It was the harbour's first glimpse of her twin-funnelled passenger liner profile.

Then after seven more good years Williams became concerned that in 1909, only four years away, his lease of his Day's Bay wharf would expire. He had put ten successful years work into Day's Bay. The Evening Post reported about 4000 had visited Days Bay on Anniversary Day 1905. His real pleasure was in running his resort and finding extra work for his commercial vessels in their slack times. By 1905 there was less commercial work available. The Union Company had bought two tugs for its own operations and there were other smaller competitors. A wharf had been built at Rona Bay and building sites were being sold. The usual civic institutions were beginning to take root in the neighbourhood, initially an unelected group calling themselves The Day's Bay Ratepayers Association. Properly constituted they would see a useful tax source in his business and in any case he did not want to run a scheduled commuter ferry service to please permanent residents.

Williams had successfully floated Wellington Steam Ferry Company Limited in 1900, a public listed company, and put his own business into its ownership. That way he raised enough extra capital to improve and expand the resort's facilities and acquire another ferry. He now put his share of Wellington Steam Ferry and its 226 acres of Day's Bay up for sale and in August 1905 it was bought by a syndicate led by William Watson of the Bank of New Zealand. Wellington Steam Ferry became a subsidiary of Watson's newly formed Wellington Harbour Ferries Limited.

Within a month an auction of 66 building sites was advertised. It seemed all Wellington protested. Harold Beauchamp, father of Katherine Mansfield appealed to the Premier, Richard Seddon, for the Government to acquire Days Bay and proclaim it a National Park "for all time". He suggested maintenance costs then would be funded by the rents from the accommodation house and pavilion and an agreed portion of the ferry company's fares. No government help was forthcoming.

After the uproar abated the auction went ahead. Wellington Harbour Ferries found revenue enough to maintain the ferry service but wanted the profits from more subdivision in Day's Bay. Its focus became property development, it had a ferry service to make the properties attractive. It lost Miramar business when trams arrived and, as expected by Williams, Harbour Board and Eastbourne Borough Council both pushed up wharf rentals. Duco was sent to the Chathams to fish and earn cash but disappeared with all hands. The council would not buy the bush-clad slopes for a reserve. The Council demanded they be allowed to buy the ferries.

Eastbourne Borough Council committed themselves to their purchase on 26 June and took over Duchess and Cobar on 1 September 1913. The timetable was increased and the service made more convenient for East Harbour residents. In 1923 the council purchased Muritai but it proved an expensive vessel to run. The paving of the Hutt Road and the extension of the bitumen to Muritai lowered ferry custom and the council was obliged to buy a fleet of buses. Duchess was sold in 1934. Muritai was taken over for Defence purposes in August 1940. Cobar was badly damaged by fire in 1948 and sold for a trawler in 1950. Cobar replacement Ocean Cruiser, a stripped Fairmile with a puny stand-in for its three V12 petrol engines, proved unreliable and did not attract the hoped-for custom.

Day's Bay House was built in 1903 for J H Williams's Wellington Steam Ferry Company. The resort hotel operation met with only moderate success and in 1913 with its immediate surrounds, 4 acres, it was sold to Miss Gladys Sommerville and building and grounds became Croydon School.

When the resort without hotel became available at the end of 1913 once again strong public pressure arose for the Government or Wellington City Council to buy it. Having no satisfaction from these organisations a Citizens' Committee was formed and it called for donations. Much the largest were from the Government, £4,000 and the Wellington City Council —the same amount—and from Mrs W R Williams, widowed mother of the park's founder, J H Williams.

The Wellington City Council announced on 11 March 1914 that councillors had visited and inspected the land in Days Bay and after a special meeting in the evening in committee resolved to buy it on the terms submitted by the deputation of citizens and the vendors. The foreshore rights vested in the company would now vest in the Wellington City Council.

Mrs W R Williams was given a copy of the following resolution by the council: "That this council place on record its deep sense of the public spirit manifested by Mrs W R Williams in contributing a sum of £1,500 towards the fund for the purchase of the Day's Bay grounds for public purposes and in recognition of her generosity hereby resolves that the reserve shall henceforth be known as Williams Park".