Canyoneering is a great way to explore some of the Southwest's national parks, but if you're not prepared for the challenges you might encounter, the activity can be highly challenging and at times even deadly.

Earlier this fall, a 74-year-old California man died while canyoneering in the Subway area of Zion National Park when he got hung-up upside down in a waterfall and couldn't free himself. The man, Yoshio Hosobuchi, was a retired neurosurgeon. He and his wife were working on their "bucket list" of things they wanted to do in their lives, and canyoneering in Zion was on the list.

However, park officials noted, the couple's only experience had been an introductory course and completing a trip through Zion's Keyhole Canyon. Unfortunately they hadn't mastered route finding and might not have had all the skills necessary to get out of trouble while rappelling. In the Subway, they made the mistake of using an "anchor that forced them to rappel down the waterfall rather utilize the anchor listed in the route description," park officials noted.

More recently, a couple that intended to canyoneer through the park's Heaps Canyon in one day had to be rescued three days later. The couple, a 41-year-old man and a 26-year-old woman, picked up a wilderness permit on the morning of October 6 to canyoneer through the 11-mile-long canyon, a canyon that requires a nearly 300-foot, free-hanging rappel, a water course, and other obstacles.

The backcountry park ranger told the couple that most people start pre-dawn in order to make Heaps Canyon a day trip. The unidentified couple replied that they were ready to spend the night if need be.

Two days later, on Monday, rangers noticed that the couple's vehicle was still parked at the trailhead to the canyon. To help look for the two, a helicopter crew was summoned from Grand Canyon National Park. Once over the canyon, spotters in the helicopter found the man and woman in the lower reaches of Heaps Canyon late in the afternoon of the October 8.

"After three days of travelling, the two had only completed about two-thirds of the canyon. Some of the canyon's most difficult obstacles still lay ahead," a park release said. "The crew was able to get a radio to the pair, who stated that they were not able to complete the canyon without assistance. On the morning of the Tuesday, October 9, a ranger and firefighter were inserted to a bench above the two canyoneers. They cleared a helispot which enabled the helicopter to land with additional rescuers. The six-member rescue team lowered a ranger from the bench 125 feet down to the stranded pair and then hauled all three people back to the bench. The two canyoneers did not require medical assistance."

Park officials noted afterwards that the search was successful in part because the hikers had obtained a backcountry hiking permit that included information useful to the searchers.

"However," the officials went on, "wilderness hikers should always inform someone of their plans along with an expected completion time. Had rangers not noticed the canyoneers' vehicle at the trailhead, it is unclear when or if the two would have been reported overdue. The group also had far less experience than most Heap's Canyon travelers. While canyon hiking (canyoneering) in Zion can be a challenging and rewarding activity, it is not one that should be entered into lightly."