For many motorists on Route 85, Organ Pipe Cactus National Park is no more than a restroom on the road to Rocky Point. So much the better. Fortunately, this most beautiful of national parks does not reveal its secrets to the casual observer. You must drive its bone-rattling backroads and hike into its canyons, take your time, and get to know it slowly.

I used to wonder how columnar cacti like the saguaro and organ pipe survive and flourish in such a "harsh" environment. Organ Pipe Cactus National Park receives about nine inches of rainfall per year, and summer temperatures can soar above 120° F, with surface temperatures exceeding 180°. But cold is a bigger threat than heat or drought to the giant cacti.

Some parts of the monument are too dry for big cactus, but no parts are too hot. They do just fine until the air temperature tops 131° F.

On a warm and windy morning, we hiked the nine-mile-loop that winds around the crown of the Puerto Blanco Mountains. We were absolutely alone, following remnants of an old mining road up a draw lined with saguaro, senita, and organ pipe cactus. After a mile of gentle climbing, the trail abruptly dropped into a huge wash, pockmarked with hundreds of footprints and dotted with knapsacks, empty water bottles and the charred remains of many campfires. We looked down the wash and saw that it led straight south to the Mexican border and El Camino de Diablo. Deserted by day, this trail was a busy thoroughfare at night.

On our way back to Tucson, the border patrol trailed us for a mile and eventually pulled us over. I felt guilty after what I'd seen -- did he know that?

"Ma'm, what's that in the back of the van, under those blankets?"

"Uh, that's a bed, sir. We've been camping in Organ Pipe Cactus National Park."

The young officer turned away, pushed back his cap. "Can I ask you just one question?" he said. My heart pounded.

"People come here from Germany, from France, from all over the world, to visit this place. Can you tell me why they come here? What do they see out there?!"

A rough gravel road just this side of the border leads to a little-used trail to Atacosa Lookout. The peach-colored CCC cabin tops a stone pinnacle with unforgettable views from the Santa Catalinas to the Sea of Cortez.

Edward Abbey spent the summer of 1968 as a forest ranger at Atacosa Lookout, and wrote about it in Confessions of a Barbarian. Today the caretaker is a furry brown canyon wren, and volunteers carefully maintain the cabin and adjacent "Edward Abbey Memorial Shithouse." The walls are papered with photocopies of pages from Abbey's books.