Daryl Hannah says she's not a ditz.

She shakes her platinum corkscrews, twists her napkin into a ball and says you can quote her on that. "I'm not like a ditz, you know."

Space cadet? "I can be, I guess."

This, after revealing she sometimes has to pull over on the highway because she forgets how to drive, that she's not ready to have a baby yet because she can't even remember to feed herself and besides, she might take the baby out and leave it in the supermarket.

The 25-year-old actress and overnight sensation in "Splash" (she was the tall blond with one red fin), who will also star as the beautiful Cro-Magnon girl Ayla in the film version of Jean Auel's "Clan of the Cave Bear" (opening Friday in New York, in February here), was in town recently to promote "Latino," a documentary on Nicaragua produced and directed by Hannah's uncle, cinematographer Haskell Wexler.

Until last year, she never traveled without her two teddy bears. On this trip, she is accompanied only by her uncle, a press agent and her Our Miss Brooks lavender rhinestone reading glasses with mauve sweater chain.

Notoriously shy (she clams up at the mere mention of her two-year live-in relationship with rocker Jackson Browne), she has agreed to meet a reporter for breakfast. At first glance, she is stunning. Up close, she is stunninger, with huge eyes, a pouty mouth and skin that looks like new pink marble.

Like somebody's ravishing kid sister, she's still a bit awkward. Kinda geeky, you know? She wears a black flouncy miniskirt, black velvet opera pumps and bumps into the table. Water glasses splosh. She apologizes. "I crashed into a chair yesterday. I was on one phone and the other was ringing and I was like leaping across the room."

She rubs her eyes like a sleepy second-grader and orders: one fried egg, a glass of milk, orange juice, herb tea.

If Vietnam had Jane Fonda, it is only fitting that Nicaragua have Daryl Hannah, an Amazon for the '80s. She did body flips in "Blade Runner" and socked Mickey O'Rourke in "The Pope of Greenwich Village." (She loosened one of his caps; he gave her a punching bag.)

She made the cover of Life (modeling bathing suits) and the Vanity Fair 1984 Hall of Fame; People's best-dressed list and McCall's "10 Best Female Bodies in America." The New York Times proclaimed her "one of tomorrow's stars," Newsweek crowned her "the Dish From the Deep," and Vogue dubbed her "Jamie Lee Curtis with lips."

If she seems to have the IQ of a shrub, those who know her say the naivete' belies a keen intelligence and hypersensitivity. Leggy and luscious, she gives new meaning to the Monroe Doctrine. Marilyn, not James.

"I went to Nicaragua twice, in April of '85 and April of '84. I guess I just went out of curiosity. I couldn't figure out what was going on from the newspapers, you know?"

She giggles, holding her glasses in her lap and twisting the chain around one index finger.

"The war was a secret war, you know? A covert war. I didn't understand what that meant. A war is a war. I went to find out what was going on. I was scared, you know, the first time I went. But as soon as I got there, I wasn't scared."

She mingled with the natives. "I was so big and blond and they just came up to me."

She met with officials. "What really affected me the most was when I went to the U.S. Embassy with a congressional delegation and heard how our representatives acted toward our elected officials. I was shocked. Of all the places I had been to, it was the only place that took away the tape recorders and took away the cameras. It was the only place that wouldn't give answers to questions that were asked. It really choked me up. I really had to hold back tears. You know, this was my embassy."

She takes a sip of water.

"We're funding a war, which directly attacks an economy. It's ridiculous, you know? We're supposed to be a parent company, I mean parent country. We're so much bigger than them. It's silly for us to be picking on them. You know?"

She sighs. "So anyway . . ."

As an actress, Hannah has been outspoken about disarmament as well as Nicaragua. But she doesn't think being a celebrity gives her opinions more weight.

"Maybe I'm wrong, but I tend to think of people who look at actors' and actresses' opinions as kind of silly, because it's a silly job to have. I mean," she laughs, "we pretend for a living."

Hannah was too young for Vietnam. She was born in 1960.

"I mean, I knew about it but I didn't understand the circumstances, really."

Her face lights up.

"You know, I just remembered. When I was a kid, it must have been like in '66, I was pretty young. We had this French nanny who would say, 'Eat all your food, zer are starving shildren in the world.' We used to send all of our clothes that we had grown out of to people who needed them. I remember thinking, 'There are starving kids in Vietnam,' so I used to put raisins in all the pockets of my clothes, cause I figured they wouldn't inspect the clothes."

She looks momentarily serious. "I might not have been able to comprehend the situation, but I still felt. You know?"

Growing up in Chicago, Hannah seemed rarely in touch with reality. Her parents divorced when she was 7, and she has little recollection of the next four years of her life. Pronounced "semiautistic" by psychiatrists, she withdrew into a magical mystery tour of the mind.

"I probably lived a little bit too much inside my imagination . . . I used to see witches and leprechauns and stuff. I actually still remember these things as if they actually happened, so I kind of like to leave that time alone and not rip it apart. Anyway, I guess the psychiatrists thought, 'She's too far gone.' "

Was it a response to the divorce?

"No," she giggles. "I was just like that."

Her nickname was "Toothpicks."

"I had ridiculous legs growing up." She cups her palms together in the air. "They were like horses' legs with these big knees and no shape."

When her mother married Jupiter Industries Chairman Jerry Wexler (brother of Haskell) in 1973, Hannah's life changed dramatically. Suddenly, the family was wealthy.

She traveled to Europe and the Caribbean. She had studied ballet since the age of 4, but as a teen-ager became interested in other art forms, especially acting. Although performing, she recalls, was as painful as it was rewarding.

"I came close to death every time." Her fear of public speaking is legendary. "I panic in situations where I have to get up and speak. I remember once I had to get up for my school in Chicago. I literally wet my pants. I'm just not good at it. Something comes over me and I can't think."

Hannah discovered politics at 15.

"I came to California. I knew I wanted to act. I stayed with Haskell for a while. He was telling me about nuclear radiation and stuff like that. That's another thing I had never heard about! I was absolutely shocked that this was going on in the world. I couldn't imagine why we would develop a kind of energy where we wouldn't know how to take care of the, uh, waste. You know? I went back to school and I said, 'You wouldn't believe what I found out.' The kids were like, 'Nucl . . . nuke-a-ler.' Nobody could pronounce the word!"

When she finished high school (she was a member of the track team and the only girl on the soccer team), she moved to Hollywood, taking courses at USC.

She was "discovered" at a Beverly Hills party. Supposedly, all the celebrities there stopped their chatter long enough to watch her dance. By the end of the evening, she had collected 25 business cards from directors, producers and agents.

She made a few low-budget films, then was cast as the punky android in "Blade Runner." She also appeared in "The Final Terror" with then roommate Rachel ("The Thorn Birds") Ward.

Then came the forgettable "Summer Lovers" and "Reckless."

"They weren't good movies. They were just stupid movies. I did a horror movie." She giggles. "I did whatever I could that wasn't too humiliating."

Hannah tends to play physical parts, strong women who fill up the screen.

"Well, I'm big. You know?"

She laughs gruffly. "I have a horse. I sort of imagine myself like her, you know? My joints are all broken. I had cartilage removed from my knee. My elbow was completely messed up. I'm certainly not as strong as I was. I also used to think I could run faster than a speeding train."

A vegetarian, she lives in the Hollywood hills with four dogs and Jackson Browne. She herself plays the synthesizer and used to be in a rock band called "Psychotic Kindergarten." Beyond that, little is known of her private life. "I think it's a detriment to you as an actress when people know so much about your personal life," she says. "They can't believe you as a character."

Has Browne been an influence? They appeared singing together on the "Sun City" video and she played the musician's girlfriend in his "Tender Is the Night" video.

"Well yeah." She smiles shyly, lowers her eyes, bites her bottom lip. "All the people around me, I guess, have been somewhat of an influence."

She awaits the release of "Cave Bear" with mixed emotions.

"This could be laughed at, you know? I did the best job I could at trying to make it as close to the book as possible and the cast fought a lot to make it right. It had problems in production. Maybe it will turn out to be a good film, but I'm sure there's going to be a lot of people saying, 'Poor Daryl.' "

She has also been shooting a film in New York costarring Robert Redford and Debra Winger (working title: "Legal Eagle") and has plans to produce several of her own films.

"At first," she says, "I'm going to be in 'em, because that's sort of my selling commodity as a producer. In that respect I'll create better roles for myself. They don't come wafting to you. For the last eight months I haven't gotten anything." Except, of course, "the James Bond type of heroine. A lot of action adventure things that don't require a lot of acting."

Perhaps her Madison-the-mermaid image has been hard to shake?

"Not really. Maybe it will be. Right now, I like it when little girls come up to me and think of me as a mermaid."

She takes her napkin and starts twisting it into a tight cylinder.

"I'm not afraid. I would like to work. I'm sure I can always work and create things for myself. I'm ambitious, I certainly know what I want to do.

"I'm looking at scripts all the time. I've got about five things in production right now. Hopefully I'll be doing one of them in the spring."

The project she is hoping to launch is a "screwball" Cinderella, a part tailor-made for Hannah, who appears far too fragile to become a movie mogul.

"It's not really tough. There are a lot of jerks but, you know, it's not really tough. I mean, there have been moments where I've said, 'If I have to do a movie like this again I will quit and be an underwater basket weaver for the rest of my life.' "

As for a political film, none are in the works.

"I've been trying to think of a story," she says, "but there aren't many tall blonds in Central America, you know?"