If you're simply walking uphill, with no rocky outcrops looming overhead, you probably don't need a helmet. But if you're climbing in areas where loose rock and falling ice are the rule rather than the exception, by all means, pack a helmet. Helmets are designed to protect your head from falling rock or ice, and they help to cushion your skull during a tumbling fall.

When you shop for a helmet, consider weight, ventilation, stability, and comfort. Helmets come in all shapes, sizes, and colors, and as long as the one you choose has a UIAA seal of approval (indicating that it holds up to international tests for strength and performance), you know you are getting a good product. UIAA tests involve dropping steel balls and pointy anvils several feet onto a helmet, so you can rest assured they are made to protect your noggin from fairly serious blows.

It used to be that people with small or odd-shaped heads had to make do with an ill-fitting helmet. However, many manufacturers now make adjustable models, which not only provide a better fit, but also allow you to wear them bareheaded or with a variety of hats and hoods.

When you try on a helmet, do so bareheaded, and then with your favorite climbing hat. In both instances, hop and bob about like a prizefighter to make sure the helmet stays in place. Bring along your own headlamp, and make sure it fits over the helmet securely, and that the weight doesn't cause the front of the lid to slide over your eyes. Check to make sure the strapping system feels comfortable when adjusted snugly around your chin. Many helmets come in small, medium, and large sizes, and a few manufacturers make children's models as well. Try on a half dozen designs, and buy according to fit and comfort.

Helmets come in two basic varieties. Most designs have an internal harness (plastic or webbing) that suspends the actual helmet an inch or so above your head. Under impact, the shell might crack or bend, then the harness stretches to absorb and dampen the remaining energy of the blow. A couple of years ago, lighter, foam core climbing helmets were introduced to the market, looking more like bicycling attire than the Coal Scuttle Helmets, the height of fashion on the Hindenburg Line. These newer helmets shave several ounces off their bulkier brothers, but aren't as durable. However, with a UIAA rating, either model is appropriate for general mountaineering. Note that suspension models are still the recommended choice for waterfall. Helmets weigh in from about 12 to 24 ounces and cost anywhere from $40 to $90.