I was exhilarated and feeling fearless, but my stomach was unsettled. I blamed Cheetah Chase.

After lunch and some animal encounters that threatened neither my limbs nor my equilibrium, I was ready to face SheiKra. I don't have much trouble with motion sickness -- really, who wouldn't feel a little queasy after riding five coasters in rapid succession? -- and am not bothered by heights or speed, but I don't like edges. SheiKra has a 195-foot drop, about half of it straight down.

At the bottom of that plunge, after I realized I had survived Central Florida's most daunting thrill ride, I knew everything would be downhill from there.

DISNEY

Thrill rides are not a significant part of Disney's repertoire of family-oriented attractions designed around sometimes-elaborate stories. With four parks in Orlando, Disney has only five actual coasters, plus two simulators.

I started at Magic Kingdom with the oldest, Space Mountain, whose overhaul last year -- new games in the queue, darker ambience, updated decor -- gave it a more contemporary feel than its age (35) would indicate; it still has plenty of thrills. On Big Thunder Mountain, the ``collapsing'' mine scenery is more threatening than the ride itself. Then to Animal Kingdom, for Expedition Everest, with its startling downhill run in reverse, and Primeval Whirl, with its spinning cars. The best of the actual coasters was my last: Rock n Roll Roller Coaster, with a high-speed launch and three inversions, accompanied by Aerosmith.

At Epcot and Downtown Disney, I designed my own coasters, then got in simulators to experience them. Once I tried them, I wished I'd drawn in more thrills. I could have redesigned them, but I wanted to spend the time riding real coasters.

UNIVERSAL

Like Disney, Universal designs its rides around stories, but is more adventurous in its thrill rides at its two Orlando parks.

At Islands of Adventure, I rode coasters that were already among my favorites: Incredible Hulk, with a high-speed launch and inventive loops, and Dragon Challenge, whose dueling inverted trains had me whooping with glee, my feet flying free.

Next door, at Universal Studios, both of the coasters lost points with me -- neither turns upside down once: Revenge of the Mummy, the only indoor coaster at the two parks, and Hollywood Rip Ride Rockit, where riders choose their own soundtrack for the experience. ``Something by the Rolling Stones would fit here,'' I thought. That's when I learned that coasters are not designed for people over 50. There was none of our music on the list. I settled for M.C. Hammer's ``U Can't Touch This,'' and we were off.

SEAWORLD

SeaWorld Orlando came late to the thrill-ride party; it didn't open its first -- Journey to Atlantis, half flume ride, half roller coaster -- until 1998. I rode it and got the usual soaking, and then tackled Kraken -- fast and floorless, with seven inversions.

It was here, on this newcomer's grounds, that I encountered the best ride of my tour, Manta, opened just over a year ago, which simulates a manta ray gliding smoothly through the water.

We sat upright, held in place by a lap bar, harness, and flaps in front of our ankles. Then the mechanism rotated our heads down, feet back. Thus suspended, we soared out over nothingness, flying on our bellies like Superman.

We climbed the inside of a loop and dove down the other side, head first, the scenery a blur of color as we rushed by at this unaccustomed angle. Then we glided up a second loop, this one with the rails twisted around it so the manta spiraled gracefully around the structure, as smooth as a stripe on a peppermint stick.

BREAKING RECORDS

The last coaster building boom saw a string of records made and broken. Coasters reached record heights -- 200 feet, then 250 and 300; now there are two coasters taller than 400 feet. At least five coasters reach speeds of more than 100 mph. The traditional enclosed sit-down car has been replaced by stand-up coasters, suspended cars, floorless cars. There are more ways of being turned upside, of feeling weightless, more coasters used in story-telling, more built with water elements or super-fast launches.

``It's like filmmakers or musicians -- whenever you have something that is built within the creative realm, people look at it and say, `What can we do to make this bigger, better, more impressive,' '' said Robb Alvey of ThemeParkReview.com.

Although no Florida coasters approach height or speed records, they do form a diverse group.

In four days, I had ridden 20 coasters and been turned upside down so many times I lost count. I had gone through basic vertical loops, diving loops, Immelmann loops, a pretzel loop and the world's only non-inverting loop; carousels, batwings, zero-gravity rolls, cobra rolls, simple corkscrews and interlocking corkscrews. My stomach had objected only once.

I considered this collection, representing some of engineering's most creative coaster designs. Then I got in line to ride Manta again.