Every summer seems to have a big B.O. whale watch more ominous than “Moby Dick.”

It’s about the fear that some major, effects-driven release won’t make its theatrical release date. That dread plagued “Terminator 2,” which was delayed two weeks, and “The Last Action Hero,” which probably would have benefited by postponing.

This year the industry wants to know if Universal’s “Waterworld” can be ready by July 28. Universal reps insist it’s not a problem. Still, down-to-the-wire post-production has the exhibitors sweating. Reports continue to swirl about complicated optical work that could put the picture out of the running if there’s the slightest glitch in the lab.

Industry trackers say the studio cannot afford to delay the picture more than a week if it hopes to benefit from summer playtime. A longer wait would likely mean a Thanksgiving berth for “Waterworld.”

With “Cutthroat Island” already vacating the frame, another major departure could have serious impact on the overall summer box office. August is now rife with low-expectation genre and niche-appeal product, with only Sony’s “The Babysitter’s Club” and New Line’s “Mortal Kombat” expected to show any commercial zing.

Sony is apparently watching the “Waterworld” situation closely, prepping its “Mary Reilly” to fill its slot, if necessary.

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