When you think of what could be stolen from a retailer to the outdoors set, the possibilities are almost limitless: backpacks, binoculars, first-aid kits , hiking boots, insulated clothing, sleeping bags, tents, cook stoves, knives, compasses, fishing gear, snorkeling masks, kayaks, skis, snowshoes, mountain bikes. Oh, and cash, of course. But at least not the rock-climbing walls that many of those types of stores now feature, right? Wrong - in the case of Outdoors Inc. in Memphis, Tenn., anyway. One day last week, staffers noticed that its wall had disappeared from the lot where it had been available to customers or for rent to organizers of festivals and other events. The wall is valued at $30,000. But it couldn't have been easy to swipe, considering that it stands 30 feet high, weighs 6,000 pounds, and is fitted with lots of raised handholds for climbers to grab. What's more, as co-owner Lawrence Migliara mused: Why would someone take that much of a risk? The item was recovered after an employee of the Shelby County Airport Authority reported seeing it abandoned near Memphis International, 12 miles from the store. Police are investigating. With so many sets of fingerprints on it, though, they may have to look for other clues to catch the thief.