Just when you thought it was safe to go back into the water at Hyannis Port . . .

"The Kennedy Women," which spans five generations in 895 pages, arrived in bookstores Monday and is already No. 15 on the Wall Street Journal's best seller list. Within two weeks, insatiable Kennedy-philes can pick up "The Other Mrs. Kennedy," 512 pages about Ethel Skakel Kennedy, with surprisingly little overlap with "The Kennedy Women."

Those who can't wait for the second book can check out an excerpt in this week's New York magazine, detailing Mrs. Kennedy's sometimes bizarre behavior in the wake of Robert F. Kennedy's assassination. Those who can't lift the hefty first book can wait for the planned CBS miniseries.

Is there really so much interest in the women behind the Kennedy men? The two publishers, Villard and St. Martin's Press, are banking on it. The books' sometimes fresh revelations about the tragedy, dysfunction and scandal surrounding the Kennedy women -- as well as Jacqueline Kennedy Onassis' recent death -- began showing up in gossip columns earlier this year, whetting public appetites.

Villard has 200,000 copies of "The Kennedy Women" in print, at $27.50 each -- expensive for a book aiming at best seller lists, but a relative bargain because of the book's sheer size. The Book of the Month Club has chosen it as a main selection.

St. Martin's plans a first printing of 250,000 for "The Other Mrs. Kennedy" and will back that up with a $150,000 advertising campaign for the $25.95 book. It also will be offered through the Literary Guild and Doubleday book clubs.

In separate interviews, both writers -- Laurence Leamer of Palm Beach and Georgetown, Jerry Oppenheimer of Chevy Chase -- stressed they became interested in their subjects because the Kennedy women had long been background figures in the lives of the Kennedy men. This was fresh territory.

Although both are former journalists who have written other biographies, neither author was a Kennedy expert when he set out.

Mr. Leamer spent five years on researching and writing; Mr. Oppenheimer worked for four.

They agreed that the mythic fortress designed to keep Kennedy biographers at bay has begun to crumble in recent years. For "The Kennedy Women," Mr. Leamer spoke to several Kennedy women, including sisters Eunice Kennedy Shriver, Patricia Kennedy Lawford and Jean Kennedy Smith. Mr. Oppenheimer was helped by Ethel's family, the Skakels, for his book, "The Other Mrs. Kennedy." (Kathleen Kennedy Townsend, Ethel's daughter and a candidate for lieutenant governor in Maryland, cooperated with Mr. Leamer, but did not respond to The Sun's request for comment on either book.)

But there, the similarities end, and a little restrained sniping begins, separated by less than five miles of Wisconsin Avenue, fTC the route from Mr. Leamer's Georgetown apartment to Mr. Oppenheimer's Chevy Chase condominium.

Mr. Oppenheimer on Mr. Leamer: "They keep pushing the fact that his book is different because he got access, but that access meant very little. He didn't get to converse with them about anything of substance."

Mr. Leamer on Ethel Kennedy, a minor figure in his book (although her sisters-in-law, Jackie and Joan, figure prominently): just read the excerpt. She mistreats her staff. I wrote about one incident like that. The endless repetition over the years doesn't add much. I devoted as much space to her as I needed to tell her story."

Mr. Oppenheimer: "Well, I found 300 more pages to write [after the death of Bobby Kennedy]."

Early reviews on Mr. Leamer's "The Kennedy Women" have been mixed, ranging from "frequently fascinating" to "goopy." Reviews Mr. Oppenheimer's book are not expected until September, the official publication date of "The Other Mrs. Kennedy." Publisher's Weekly noted in May that both authors have "written biographies praised more for bulldog research than authorial analysis."

But reviews have never been the point when it comes to Kennedy books. There is, for whatever reason, a rich vein to mine here. Mr. Leamer and Mr. Oppenheimer have their theories. Different theories, not surprisingly.

"It's not a voyeuristic thing at all. It's 170 years of social history," says Mr. Leamer of the interest in his book. "I really wanted people to learn something about the times."

This meant extensive research into Catholicism, the medical practices that affected the life of Rosemary Kennedy, even the ship's logs of Boston-bound Irish immigrants. He also became the first journalist to visit St. Coletta's in Wisconsin, where the lobotomized Rosemary Kennedy lives. Ultimately, Mr. Leamer had to cut 150 pages about the life of Bridget Murphy, paternal grandmother of Joseph Sr.

"Women have read the book because it's a history of women, who are missing from other accounts," Mr. Leamer says.

But Mr. Oppenheimer, while he also researched his subject exhaustively, says of the Kennedys: "They make juicy copy. Whatever Larry's high-flung theories are, I think there is an incredible fascination with the family. From 1960, then the follow-up scandals, we adopted this family as our royalty. I don't think the American public cares about 12 generations, they want to read the 'juicy bits' as they say on Monty Python."

Both writers supply said bits. But they also grind to dust the idea that marriage or birth into this royal family provided one with a charmed life, even before the tragedies of the 1960s. It's hard work being a Kennedy woman and often thankless work at that.

"The themes are depression and denial, and a refusal to look into the past," Mr. Leamer says.

Mr. Oppenheimer agrees, going so far, in an interview, to hypothesize that Ethel Skakel might have had a much happier life, married to some executive in Scarsdale, free to ride and play tennis in blessed obscurity.

"The Skakels were really a great bunch," he says. "I hate to throw this on the Kennedys, but maybe by becoming a Kennedy, Ethel had a worse life than she might have."

Mr. Leamer ends his book with a chilling scene in which Rose Kennedy, who turned 104 last month, watches a videotape of her family's history, with all the sad scenes excised. Fragile, unable to speak, the matriarch's awareness of the world around her is a mystery. It is unclear if she knows her grandson David, Ethel's son, is dead, much less that he died of a drug overdose. (One of the key revelations in Mr. Leamer's book is that Sen. Ted Kennedy has, for years, manufactured quotes for his mother and given them to the press.)

But she may understand more than most people think, says Mr. Leamer, who also worked with Kerry McCarthy, Mrs. Kennedy's niece and the author of her own unpublished biographies of the family.

"She told Mrs. Kennedy one day about my book," he recalls, "and she turned her head away in disgust. Then Kerry said, 'Oh, no, it's not going to be like one of those other books,' and she seemed enthusiastic."

But neither Mr. Leamer's book, nor Mr. Oppenheimer's book, has been edited as carefully as the videotape Rose Kennedy so enjoys. In both volumes, the dark side of being a Kennedy, especially a Kennedy woman, is definitely there.