The park was created in 1978 when Great American Recreation (GAR), the new owners of the recently combined Vernon Valley/Great Gorge ski area, wanted to do something with the ski area during the off season. Two years earlier, in 1976, they had followed the trend of many other ski areas at the time and opened a 2,700-foot-long (820 m) alpine slide down very steep ski trails.[9] Gradually, Waterworld and Motorworld came together at the base of the mountain to form one of North America's earliest modern water parks,[3] which was originally called the Vernon Valley Summer Park.[10] They started out with two water slides and a LOLA race car track in the summer of 1978, and then more waterslides and a small deep-water swimming pool the next year, as well as tennis courts and a softball field. Finally, Motorworld was carved out of the swampy areas the ski area owned across Route 94. Ultimately, the small park consisting of the alpine slide and two water slides evolved to a major destination with 75 rides (35 motorized, self-controlled rides and 40 water slides).[3]
By the 1990s, the park was being advertised as the world's largest water park.[11][12] Additionally, during the 1990s, up through the park's final season, and into 1997, Action Park maintained a website at the domain actionpark.com, on which visitors could find information about rides, directions to the park, and lodging, and even enter a lottery for a chance to win park tickets.[13][14] Action Park's most successful years were the mid-1980s. Most rides were still open, and the park's later reputation for danger had not yet developed. In 1982, the deaths of two visitors within a week of each other and ensuing permanent closure of one ride took place, but that hardly dampened the flow of crowds.[15] The park's fortunes began to turn with two deaths in summer 1984 and the legal and financial problems that stemmed from the lawsuits. A state investigation of improprieties in the leasing of state land to the park led to a 110-count grand jury indictment against the nine related companies that ran it and their executives for operating an unauthorized insurance company.[16] Many took pretrial intervention to avoid prosecution; head Eugene Mulvihill pleaded guilty that November to five insurance fraud-related charges.[17] Still, attendance remained high and the park remained profitable, at least on paper.
The park entertained over one million visitors per year, with as many as 12,000 coming on some of the busiest weekends.[3] Park officials said this made the injury and death rate statistically insignificant. Nevertheless, the director of the emergency room at a nearby hospital said they treated from five to ten victims of park accidents on some of the busiest days, and the park eventually bought the township of Vernon extra ambulances to keep up with the volume.[3] In September 1989, Great American Recreation negotiated a deal with International Broadcasting Corporation that would result in the sale of Vernon Valley-Great Gorge, and Action Park, for $50 million.[18] IBC, however, backed out of the deal, feeling the site was not suitable for their needs upon further inspections of the properties.[19][20] In September 1991, Great American Recreation attempted to petition the Vernon Township Committee to put a referendum on the November ballot that, if passed, would have legalized the operation of games of skill and chance at Action Park. On September 23, the petition was rejected by the committee because only 643 of the 937 signatures on the petition came from registered voters. [21] A few rides were closed and dismantled due to costly settlements and rising insurance premiums in the 1990s, and at last the park's attendance began to suffer as the recession early in that decade reduced visitation. In early 1995, GAR operated Vernon Valley-Great Gorge with no liability insurance.[22] New Jersey did not require liability insurance, and GAR found it more economical to go to court than purchase liability insurance since they relied on their own self-insurance.[23][24] GAR purchased liability insurance from Evanston Insurance Co in May of that year to cover Action Park, as well as Vernon Valley-Great Gorge's skiing facilities.[25]
As 1995 progressed, GAR's financial woes continued to accumulate. First Fidelity Bank, who lent $19 million to GAR, and some 15 other connected corporations, filed suit against them in an effort to begin the process of foreclosing on the debt owed to them.[26] Law firms owed money for services rendered between 1991 and 1993 also began filing suit.[27] As November rolled around, GAR negotiated a deal with Noramco Capital Corp, and the Praedium Fund of CS First Boston, in which they would purchase the debt owed to First Fidelity, temporarily fending off an impending foreclosure.[28] In February 1996, the creditors who had taken on GAR's debt petitioned to force GAR into bankruptcy over the $14 million owed by the struggling company.[29] GAR filed for Chapter 11 protection that following March, but remained optimistic that they could regain their financial footing "within a year."[30] Action Park closed at the end of the season as usual on Labor Day, September 2, 1996. Going into 1997, GAR remained optimistic that Action Park would open as expected on June 14, in spite of massive layoffs that occurred at the end of the ski season.[31] The opening date was pushed back to June 28,[32] then mid July.[33] On June 25, 1997, GAR announced the cessation of all its operations, including Action Park.[34]