UNIVERSAL CITY, CALIF. — THIS summer, moviegoers who emerge blinking from the 18-screen cineplex here adjacent to Universal Studios may be struck by a sense of deja vu.
Some of the same Hollywood blockbusters are debuting in the theme park as thrill rides. Today, ''Casper,'' the feature film, is also opening simultaneously as a mansion haunted by the computer-generated apparition.
On July 1, ''Apollo 13'' will launch as a movie and an amusement-park adventure. Later in the summer, Kevin Costner's $175 million ''Waterworld'' will make a splash both here as a daredevil action show and in cinemas across the nation.
Following a trend that has been accelerating through the 1990s known as ''theming'' (rhymes with scheming), amusement parks and movie studios are teaming up to both make up deficits from past money-losing years and recoup costs from some of the most expensive films ever made.
''Theme parks and movie studios are becoming ever more savvy in harnessing the millions they are spending on marketing,'' says Tim O'Brien, an industry analyst for Amusement Business Magazine. ''If they are going to be spending tens of millions to get consumers to do something, it makes sense in general to help each other out with cross promotion.''
Americans spend 40 percent of their yearly entertainment income between Memorial Day and Labor Day, which means open season by marketers for their hard-earned leisure dollars begins this weekend.
The double-whammy marketing technique is being employed more than ever at theme parks this year because of the huge number of Hollywood blockbusters vying for attention.
''There are more major, Hollywood films headed out of the gate this year than any time in probably two decades,'' says Christopher Lanier, president of Motion Picture Intelligencer, a Beverly Hills firm that tracks the industry.
Six of this summer's biggest pictures are estimated to have cost more than $70 million apiece. Another seven are estimated to have cost between $50 and $70 million. The list is led by ''Waterworld,'' which is the most expensive film ever made.
Last summer, 47 films were released during Hollywood's biggest box office ever ($2.2 billion). This year, 56 films are due out.
''Hollywood films are making more than ever but they are also costing more to make, and profit margins are dwindling,'' says Mr. Lanier. ''Studios need to recoup costs any way they can.''
That's why theme park tie-ins, as well as foreign distribution, video earnings, sales to cable, and merchandising are an increasingly important addition to the bottom line. Sometimes, mega-flops such Arnold Schwarzenegger's ''Last Action Hero,'' make more money abroad than in the US.
For Time-Warner Enterprises, which both produces ''Batman Forever'' and is half owner of Six-Flags Theme Parks nationwide, money spent to promote its movies also brings customers to its theme parks to participate in the same movie fantasies. At the same time, the strategy goes, park visitors who first encounter movie-themed amusement attractions are more likely to seek out the feature films that spawned them.
''The money we spend in marketing works double-time for us,'' says Robert Pittman, president of Time Warner Enterprises, which is producing this season's ''Batman Forever'' as well as placing Batman-themed entertainment in several of its parks. Out of an estimated $60 million to $70 million spent on park advertising, about $10 million to $20 million will go toward Batman promotions.
The theming and branding idea has been growing in recent years according to theme park historian Paul Rubens, an editor of Park World, an amusement park industry trade publication.
''Theme parks lost their way in the 1980s as they continued to add rides helter-skelter seemingly without a plan,'' he says. ''They are now recapturing their reasons for being, which is to introduce themed attractions and adventures to take people out of their everyday world and let them actually live in the fantasy of motion pictures.''
All told, 400 American theme parks have added about $270 million in features this year, according to Mr. O'Brien. If there is a down side to theming, say observers, it is the risk that a given movie may do poorly at the box-office.
''If the motion picture lacks appeal, the ride will flop and related merchandise will not move off the store shelves,'' says Mr. Rubens. Noting that Universal's ''Casper'' attraction this year is the first ever to open the same day as the feature film is released, he adds, ''usually they wait until a film is an established hit.''