Cooler. Check. Coppertone. Check. Ray Bans, umbrella, flip-flops. Ditto. "Remembrance of Things Past." Whoooaaa.

Forget it. You'll never read it. There's still sand between the pages from last summer, and zinc oxide smeared on the dust jacket from the summer before that. You pack it anyway. After all, Proust looks great on the beach chair. Then, stealthily slip Robert Ludlum, Jackie Collins, Elmore Leonard, Danielle Steele and Lawrence Sanders into the bag.

Oh, the deliciousness of it. Everything you always wanted in a book, and less. Literary Lean Cuisine.

We are what we read, especially when it comes to beach books, a phenomenon so familiar to publishers it's now become a generic term: beachbook.

What makes a boffo beachbook?

"There's a general assumption that a beachbook is slightly trashy," says Simon & Schuster Editor in Chief Michael Korda, author of "Queenie." "I don't think that's necessarily the case."

"It's a book you find wonderful to relax with," says Harvey Ginsberg, senior editor with William Morrow. "Pure pleasure reading as opposed to duty reading."

"I'm not sure it's all fun and games," says author Sanders, who has two books on the best seller lists this summer, "The Fourth Deadly Sin" in hardback and "The Passion of Molly T." in paperback. "It's got a little bit more to it than that."

"Vivid. Amusing," says Stuart Applebaum, spokesman for Bantam Books. "Sometimes eyebrow raising. Occasionally titillating. A little more racy than hospital books."

"A little kooky," says Sanders.

"Upbeat and sexy," adds Korda. "A more or less happy ending would be mandatory. A best-selling novel, with a human story. Some glamor. I don't think anybody's going to take Henry Kissinger's memoirs away for the summer."

In the past, there were two traditional publishing seasons, spring and fall. Now, more and more houses are bringing out major books in midsummer, hoping to cash in on the beachbook market.

One publishing firm, Bantam, deliberately pushed up the publication date of the current number one nonfiction best seller, the autobiography of ace test pilot Chuck Yeager, from August of this year to June for just that reason.

"I got a copy of the galleys for 'Yeager' over Christmas holidays last year," says Bantam's Applebaum. "I read it and loved it. The second week of January I went into the office and said, 'We gotta be out for the Fourth of July.' "

Bantam and Yeager both agreed. With 400,000 copies in print and a lock on the number one slot, "Yeager," according to Applebaum, "owns the summer."

But that didn't stop Bantam from pushing another contender for sizzling beachbook status, appropriately titled "Beaches."

"No question about it," says Applebaum. "We deliberately put 'Beaches' on sale because it was suggestive of the season."

The book, a first novel by Iris Ranier Dart (daughter-in-law of the late Justin Dart, entrepreneur and Reagan confidant), is being touted as a "Terms of Endearment"-type tale of friendship between two women. Over the Fourth of July weekend, Bantam -- thinking bicoastal -- hired a plane to fly over beaches from Coney Island to East Hampton, and Malibu to Laguna, trailing the streamer: "DON'T JUST SIT ON IT -- READ IT -- BEACHES."

The ingredients of the perfect beachbook are more hotly debated than what goes into a prize-winning chili.

"I think in general, it has to be lightweight," says Eliot Kaplan, managing editor of Gentlemen's Quarterly. "In actual size and content."

Not so, says free-lance writer Jesse Kornbluth. "The summer is when you do your serious reading." He spent one recent, "rewarding" vacation reading "Autonomous Technology" by Langdon Winner. This summer, he's reading -- you guessed it -- Proust.

Kornbluth seems to be the exception, although Jayne Anne Phillips, whose "Machine Dreams," just released in paperback, is bound to be in more than a few beach bags this summer, says she has never indulged in what used to be called "hammock reading."

As a teen-ager, she brought Willa Cather and the Bronte s to the beach. And don't even mention the phrase "pulp paperback."

"I'm just not interested in Jackie Collins under any circumstances," she sniffs.

Mary McCarthy, author of "The Group," agrees. "I don't like junk food and I don't like junk literature," she says.

But syndicated gossip columnist Liz Smith says there's nothing better than empty literary calories.

"I think Jackie Collins' stuff is really good trash," she says. "She puts the love scenes in italics. I think that's the funniest thing I've ever seen."

Smith predicts that Collins' "Lucky" will be a hot beachbook this summer, as well as "Final Cut," the nonfiction expose' detailing the disastrous making of the flop film "Heaven's Gate."

After all, says Smith, "Money and business is the new sex."

Aside from the subject matter, says one well-known author, a beachbook "has to be a good read. Somewhere between trash and literature."

No one fits that category better than Elmore Leonard, prolific author of westerns, detective stories and the wildly popular "Glitz." With Leonard, you never feel as if you've just eaten two dozen Hostess Twinkies. You don't hate yourself in the morning.

"I don't think of them as beachbooks," Leonard says. "I think of my work as entertainment, primarily, on a very realistic level. I want the reader to turn pages."

Leonard says there's no such thing as good trash.

"I can't read Erich Segal," he says wearily. "I can't read Sidney Sheldon. I can't read Judith Krantz or Harold Robbins." Even at the beach.

Leonard is reading Ann Beattie's new novel, "Love Always."

Beattie, who just returned from the Riviera, says, "In Europe, nobody's reading anything but magazines with stories about Princess Michael."

Nora Ephron, whose "Heartburn" was a boffo beachbook several summers ago, is reading "Savage Grace," the tragic story of the Baekland family with all the necessary ingredients for a successful sand saga: power, money and murder.

"It's the perfect beachbook," raves Ephron, "because you only have to read it one or two minutes at a time."

Sanders, who describes his books as "intelligent entertainment," says people tend to "thaw" at the beach, mentally and physically.

"I would suspect that unless they have pretty good self-discipline, their brains turn to mush," he says.

Korda agrees. "The summer's a time for self-indulgence. It's the same reason people eat ice cream at the beach. You figure you'll have a good time and you want books that will give you a good time."

This season, the books mentioned most frequently under that heading are Dominick Dunne's "The Two Mrs. Grenvilles," Diana Vreeland's "DV," John Irving's "The Cider House Rules" and "The Kennedys," which was a big beachbook in hardcover last summer and now is in paperback.

Beattie is reading "Queenie." So is actress Jane Seymour. Liz Smith is reading Hannah Pakula's "The Last Romantic," Jack Kent Cooke is reading Larry McMurtry's "Lonesome Dove," and Larry ("Best Little Whorehouse in Texas") King is wading through the collected works of spy thriller master Charles McCarry. ("I sure don't wanna call it beach literature, 'cause it's better than that," growls King.)

Men seem to gravitate toward biographies ("Yeager," "Iacocca"), anything by Robert Ludlum, and Tom Clancy's current best seller, "The Hunt for 'Red October.' " Women are drawn to Danielle Steele ("he played her body like a violin") and the best-selling French novel "The Lover," by Marguerite Dumas.

Author Peter Maas ("Serpico," "Marie") is perusing an advance reading copy of E.L. Doctorow's new novel, "World's Fair."

Which raises the question of whether people actually read beachbooks or just acquire them, in the never-ending search for the latest status symbol.

Steven Aronson, coauthor of "Savage Grace," says he took two books to the beach last weekend, Haile Selassie's biography, "Emperor," and Barbara Pym's "Crampton Hodnet." He didn't read either one of them.

Hordes of Hamptonites are clutching William Gaddis' "Carpenter's Gothic," although one summer native confided, "No one's actually read it."

"It would not be good to lose your place in it," says McCarthy, who has just finished "Carpenter's Gothic," adding, "I wouldn't consider it beach reading."

"I don't know how people read at the beach anyway," says Aronson. "I was at Jones Beach recently and the only thing people were reading was The Daily News."