THE COASTER CROWD

When it comes to Florida's amusement parks, there are two types of riders: Those who like to have their internal organs rearranged as they zip along at skin-flapping speeds, and those who prefer to keep their innards immobile. Annie, I discover, belongs in the first category.

After riding the slalom-like Gwazi, a mammoth double wooden coaster with a seemingly continuous number of spirals, my oldest turns to me and shouts, ''That was awesome!'' Her eyes gleam. The ribbons at the ends of her braids hang tattered from high wind velocity.

My youngest -- someone who gets car sick on the drive to Dadeland Mall -- isn't so sure. As the bar clamps us into place aboard the Scorpion, a steel coaster with a 360-degree loop and 60-foot drop, she looks worried. ''I want to get off,'' she says suddenly as the cars lurch forward. Too late. She makes Annie promise not to put her arms up. She closes her eyes and grips my hand. ''At least it's safe,'' she mutters.

Lucy is more than willing to sit out while her sister and I climb into Phoenix, a large wooden sailing vessel that swings like a pendulum and turns several full loops, holding riders upside down for an unbearable amount of time. The sensation even disturbs Annie, who keeps yelling, ``Oh, Mama! Mama! I don't have a good feeling!''

I learn that I am no longer the kid who seeks out the steepest coasters, the scariest loops. At 42, I have suddenly become motion intolerant.

Online, I discover a sensible explanation for the dizziness and vertigo. It's because I'm old. The American Institute of Balance's website explains that changes in the equilibrium portion of the inner ear -- the fluid that informs the brain where and how fast the head is moving -- can be part of the natural aging process.

Still, I re-claim some of my old zest by the end of the first day, when a skinny boy cuts in front of us in line and runs ahead up the ramp to get another turn on Gwazi before the park closes at 8 p.m. I grab Annie's hand and sprint after him. Just as we're about to overtake the kid, my daughter drags me to a stop and looks embarrassed. ''Mom, you're out of control,'' she whispers.

LIFE LESSONS

Our carefully-planned park strategy works for the most part. Lucy and Grandma sample some of the kiddie rides in Land of Dragons while Annie and I ride Gwazi. They stand on a bridge overlooking Tidal Wave so they can get soaked by the giant breaker Annie and I create when our boat makes the 55-foot crash landing.

On rides that issue warnings for people with high blood pressure, Grandma quietly bows out and we use an unofficial version of ''child swap.'' The feature, available at Disney parks and most others, is set up so adults with kids too short for some attractions can still ride. It allows one adult to wait with the child, while the other takes a spin on the ride. When that adult returns, the next adult can hop on the ride and hand off the child.

In our case, some rides allow me to hop on with one child, while Grandma waits with the other at the front of the line. At the end of the ride, the attendant allows me to stay on the ride and take the next child, without returning to the end of the line.

We discover that height restrictions are taken seriously. At the entrance to Ubanga Banga Bumper Cars, the attendant pulls out a right angle to accurately size up one young boy against the metal measuring stick. Another attendant asks Lucy to step out of the car on the Cheetah Chase coaster. He shakes his head when she doesn't measure up. ''She can't ride this,'' he apologizes as she runs down the exit ramp in tears to wait with Grandma.

Oh yes, there are heartbreaks when high speeds are involved. During our visit, rides are shut down several times due to technical difficulties. We wait 40 minutes for one thrill, only to have the ride close moments before we climb aboard. I chalk it up to a life lesson -- an unplanned turn of events that is measured by your willingness to bounce back and try again.

The rides, too, seem to be a test. Not to get too philosophical about a scream machine, but when you've plummeted 55 feet or hung upside down 100 feet in the air, some of those old fears -- elevators, thunderstorms, dark rooms -- seem bearable. You realize it's OK to be scared. You're a survivor.

Even Lucy, my erstwhile partner in queasiness, ends our first day at the park on an optimistic note. As we slog along with the sweaty masses to catch the trolley back to our car, she glances at Gwazi and issues a little prayer.

``Oh, I hope I grow tonight.''