Whenever I think of climbing, my mind always drifts to beautiful mountain peaks and long trails lined with every type of wildlife imaginable. For some climbers, however, it's all about the vertical.

At one time, El Capitan in Yosemite National Park was considered impossible to climb and for good reason. Each of the many routes to the top of El Capitan is long and treacherous, testing both the climber's skill and his endurance. Of course, it's also the ultimate adrenaline rush for people who enjoy looking at the world from the face of a rock.

Made of coarse granite and soaring 3,000 feet in the air, El Capitan is considered the Everest for big-wall climbing. Although I've seen it in person - on vacation when I was about ten - mere pictures of this monolith are sufficient to give me goose bumps.

The routes up El Capitan vary, but the most popular and most difficult is the Nose. It was first successfully climbed in 1958, and since then climbers from all over the world have aspired to reach the summit. This route usually takes two or three days to accomplish, though a few expert climbers have conquered it in just one.

A few of the routes, including the Nose, have been free climbed, but aids are definitely recommended. Unless you have significant experience (and a need for danger), ropes should accompany your expedition in Yosemite. A few climbers who thrive on challenges have raced up the Nose and other routes on El Capitan, but this is also not for an amateur.

In order to climb El Capitan, you'll access it from a trail in Yosemite. I recommend bringing along a light-weight and roomy pack, such as C.A.M.P. Rox, a 40-liter duffel with plenty of space.

I would also recommend becoming proficient at a few smaller big-wall climbs before attempting El Capitan. It might be exciting and adventurous, but it has also been the cause of many injuries over the years. If you have any qualms at all, go with an experienced guide who can "show you the ropes," as they say.

Mountain climbing isn't always as treacherous in the United States as it is overseas, but there is always the exception to the rule. Take, for instance, Mt. McKinley, which is located in Denali National Park in Alaska. McKinley is the highest peak in all of North America, and despite its unmistakable beauty, this mountain is one of the most dangerous climbs you could ever attempt.

The main issue with Mt. McKinley, of course, is the temperature. You expect freezing weather in Alaska, but the summits of this particular mountain go beyond mere frigidity. Temperatures of -50 degrees C are not unheard of, and the lowest recorded temperatures are far below that. In order to fair well on Mt. McKinley, you'll need to dress with the intention of keeping all your fingers and toes intact.

In addition to a heavy thermal coat, long underwear, a hat that protects your ears and thermal pants, you'll also want to protect your feet. This is probably the downfall of most climbers who attempt to ascend and wind up in a hospital.

The EuroSock Ascent Wool is a good choice because it provides warmth, ankle support and moisture management, while increasing circulation. Socks intended for skiing, snow-boarding and mountain-climbing are usually your best bet.

It is also important to remember that, when conquering America's highest peak, you have to deal with the nasty side effects of such high altitude. Altitude sickness is more common than you might imagine on Mt. McKinley, because climbers underestimate the need to prepare.

Before you leave, make sure you are able to tolerate the loss of oxygen and moisture in the air. On your hike, watch for signs of altitude sickness in both yourself and the people around you; if someone seems to be falling ill, an immediate descent is necessary. No one needs to die just because you want to be able to say you climbed Mt. McKinley.

Of course, the main summit of Mt. McKinley provides one of the most beautiful views in the world, and you'll have an opportunity to see enormous glaciers up close. Just be aware that preparation is needed to climb this particular mountain, so make plans before you start packing your gear.