Next week, children can enter the make-believe world of "Dark Waters," a five-part, animated miniseries. But the creator of the show, David Kirschner, (who's also the president and CEO of Hanna-Barbera) has lived in that world since he was a child."I wasn't very good at sports, so I's climb up on the top bunk of my bed and conquer the world with H.G. Wells, Edgar Rice Burroughs... and (illustrator) N.C. Wyeth, who was and is my great hero." He developed a passion for swashbuckling pirates, medieval heroes and epic adventures -- all of which are elements of "Dark Waters." The miniseries, which airs Monday-Friday at 2:30 p.m. on ch. 13, is about a young hero named Ren who lives on the planet Mer -- 98 percent of which is under water. Ren sets out on a quest to find the lost Thirteen Treasures of Rule in order to save his dying planet, which is threatened by an evil force called Dark Water. "What's interesting is I was down in my basement with my daughter last week going through a bunch of my old artwork. Sketchbooks from when I was a kid, about 10 to 14," Kirschner said. "I was just obsessed with pirates and medieval characters. it was all the same stuff you'll see in `Dark Waters.' "I don't think I've changed much since I was 10. Kirshner, 35, began his career illustrating album covers, then went on to writing and illustrating children's books. He quickly moved into animation and production -- he created and co-produced "An American Tale" and the horror movie "Child's Play," about a murderous doll. ("My sisters' dolls scared me horribly as a kid," he explained.) And, at the age of 33, he was named president and CEO of Hanna-Barbera. Kirschner doesn't fit the mold of a corporate chief. He tends to come to the office in jeans and old shirts with the sleeves rolled up. "I don't consider myself CEO material by any means," he said. "On my tombstone, beside `beloved husband and father,' I want it to say `storyteller.'" His office (as well as his home office) is filled with models and illustrations he's made, animation cels and all sorts of cartoon memorabilia. "I just couldn't have a corporate looking office with a computer sitting on my desk," Kirschner said. "I don't think I could do anything creative the entire day." At the same time, Kirschner has moved hanna-Barbera into the "90s. The company of Fred Flintstone, George Jetson and Yogi Bear is "moving into a lot of different areas it's never been before." Among those projects: -- "Capital Critters," an animated, prime-time series about mice at the White House -- a co-production with Steven Bochco. -- "Fish Police,"another animated, prime-time series (this one for CBS) that Kirschner descibes as "kind of a `fish noir' -- Raymond Chandler under the sea." -- The recent made-for-TV movie "Dreamer of Oz." -- A live-action, theatrical film of "The Flintstones," starring John Goodman as Fred. -- A theatrical movie "Conundrum," an adult thriller starring Sally field. -- The "Funtastic World of Hanna-Barbera," an attraction at Universal Studios in Florida. And, of course, "Dark Waters," perhaps the most expensive cartoon series in history at $500,000 perepisode. The average TV cartoon contains 14,000 animation cels perhalf hour -- "Dark" contains 23,000. "We put a lot of time and effort into this," Kirschner said. "We wanted to make it as good as we possibley could, everything from the animation to the music to the actors." (Those doing voices include Roddy McDowell, Tim Curry, Hector Elizondo, Jessica Walter, and Jodi Benson -- who did the voice of the "The Little Mermaid.") "And it's more than characters just conking each other on the head," Kirschner said. "It's a culmination of a boyhood adventure that really never stopped."