TUCSON, Ariz. — The most dramatic moment of our trip to Tucson came as my husband and I were hiking up a steep, narrow, rocky trail in Sabino Canyon. Faced with a big rock that required me to step up almost 2 feet, I lost my balance and tumbled into the mountainside — away from the steep slope that spilled into a cactus- and scrub-covered canyon and into the waiting arms of a spiky plant called a teddy bear cholla.

As I gazed down at the sharp spines stuck into my flesh like so many acupuncture needles, a million thoughts raced through my mind. Step-aerobics classes and balance exercises in a gym can't begin to prepare you for the challenges of a trail rated in one of our books as "moderate, steep for the first mile." And I had that sensation of, "Uh oh, we're not in New York anymore."

It was precisely to escape the overcast, leaden skies of a New York winter that my husband and I — who are on a semiofficial quest to visit all of this country's national parks — scoured the parks Web site — /www.nps.gov — to find a suitable location in the Southwest. That's how we ended up in Tucson, which boasts 350 days of sunshine a year and 65-degree average highs in January.

The city is straddled on either side by the eastern and western chunks of Saguaro National Park. Another great hiking destination, Sabino Canyon, is in the Santa Catalina Mountains north of the city.

We also spent two days in an overnight stargazing program at the Kitt Peak National Observatory, about 60 miles southwest of Tucson. The observatory is home to the largest collection of research telescopes in the world and the city has adopted low-lighting ordinances to try to cut down on light pollution. From the top of Kitt Peak, you can see Tucson glimmering off toward the northeast, and more ominously, the bright glow of Phoenix some 100 miles to the north.

Still, the laboratory boasts of having some of the finest skies in North America, in part because of the mostly clear, dry weather — the same conditions that make the city a magnet for retirees and the surrounding mountain ranges a paradise for hikers.

We started at the visitor center on the western side of Saguaro Park, where helpful rangers pointed out the trails to Wasson Peak. At 4,687 feet, this popular destination offers stunning, 360-degree views of the city and surrounding Sonoran Desert.

Soon, with our 2-liter bladders strapped on our backs, we were heading up the Sendero Esperanza, or Trail of Hope, through a sandy desert wash and up a ridge that intersects with another trail to the summit.

Overhead were brilliant, nearly cloudless blue skies and all around us, miles of rugged trails flanked by oddly shaped desert plants and cacti uniquely adapted to one of the hottest, driest regions on the continent.

For my money, the undisputed star is the namesake saguaro, the entertaining, sometimes goofy-looking cactus that dots the rugged slopes of the mountains around Tucson.

Towering over the desert scrub, the saguaro can grow to over 50 feet and survive up to 200 years. It doesn't even produce its first branches until it's lived half a century. And it's the sight of two such branches extending out and upward that at times make them look almost human — call it the "I surrender" pose.

The visitor centers in both park districts have many brochures about the amazing saguaro (pronounced sah-WAH-roe) and other desert wildlife, but we were also glad to have stumbled upon the Summit Hut, a local outdoor gear store whose staffers are a fount of information about local trails. They recommended Betty Leavengood's "Tucson Hiking Guide" (Pruett Publishing, $16.95) which served us well for the remainder of the trip.

It was her book that described Sabino Canyon's Blackett's Ridge Trail, site of my close encounter with the cactus, as "moderate, steep for the first mile." She's probably right about the "moderate" tag, since other hikers, some a good 20 years older than us, were scampering up and down the trail with no problem. She was definitely right when she described it as "one of the best little hikes" in the area, with dramatic views of the peak and canyons in the rugged Santa Catalinas.

After I overcame the initial shock of being stuck, I managed to flick off the little piece of branch in my flesh so my husband could start extricating the razor-sharp spines with our trusty tweezers. (Note to the accident-prone, and even the experienced adventurer: Never travel without a first-aid kit!) When the very minor operation was over, my palm was pretty much a bloody mess. I was shaken to the core, but there was no way I was going to admit defeat and go back. We were rewarded for our perseverance: At the bottom of the hill we spotted a roadrunner skittering across the pavement to inspect a desert tortoise inching across a sandy wash.

Later, over giant burritos at a restaurant in one of Tucson's many strip malls, I was almost glad about the mishap — it made coming back down the mountain even sweeter.

I had arrived at more or less the same conclusion as had Edward Abbey, the controversial nature writer and fervent environmentalist who was quoted in the national park newspaper: "You can't see anything from a car. You've got to get out of the contraption and walk, better yet crawl, on hands and knees, over the sandstone and through the thornbrush and cactus. When traces of blood begin to mark your trail you'll see something, maybe."

We barely scratched the surface in our all-too-short visit to Abbey's beloved desert. That's why we want to go back — so we can leave the contraptions of our urban life behind and see something more.