Surfers consider Oahu's famous Banzai Pipeline with its mountainous waves the original Hawaiian rollercoaster ride. But for landlubbers, Maui's Route 360 is the ticket. Known to the world as the road to Hana, breathtaking vistas enliven the senses around every one of its 112 turns. Traveling east, spectacular waterfalls capture the passengers' side gaze, while rocky cliffs overhanging the deep blue Pacific can distract the driver. Around almost every bend, danger lurks as cars sometimes fishtail out of their lanes into oncoming traffic.

Weary of tourists stopping on blind curves to snap a few photos for the folks back home, we decided to take a road less traveled. In fact, my wife, two young daughters, and I found an unmarked Jeep trail somewhere beyond milepost three that (we thought) led to a secluded beach. Less than 50 yards off the Hana Highway, we were enveloped by lush jungle vegetation when the road narrowed to a tight trail that looked as if it doubled as a riverbed after heavy rains. The gravelly descent had us reaching for the security of the four-wheel-drive lever of our Grand Cherokee. We emerged from a tunnel of thick vines and native foliage, and I was a bit frazzled to see a sheer cliff and the ocean several hundred feet below. Up ahead was a clearing wide enough to turn around in and abort this excellent adventure. The only obstacles in our path were two boulders--one too wide to drive around, the other just barely too tall to straddle. I'd have to climb over them.

I turned to my wife (strictly an on-road sedan driver) and told her she'd have to get out and spot me. Her blank expression told me all I needed to know. She had no idea what I was talking about. I explained that she'd have to make absolutely sure my tires were where they had to be, as I had no desire to get stuck in a zone where I was uninsured and contractually forbidden to enter. Yes, not only was this excellent adventure ill-advised, it also was illegal.

"Most standard rental agreements don't let you take a rental vehicle of any kind onto an unpaved road," says Chris Payne, spokesperson for the Dollar Thrifty Automotive Group. "This has been the standard in the industry for more than a decade and isn't exclusive to Hawaii."

Though hopping these volcanic rocks would be simple enough in our trail-rated rental, if my spotter and I weren't in sync, I could easily crease this new Jeep on the rocks or damage something underneath.