Once more it begins. A new community has formed near 7,200 feet in the wilds of the Alaska Range, marked by a rainbow of red, yellow, blue and green nylon.

Welcome to Kahiltna base camp, the starting point for most assaults on the 20,320-foot summit of Mount McKinley. On a clear day, North America's tallest mountain looms above the mountaineers camped along the seasonal airstrip here, and throngs of tourists fly in ogle the climbers and admire the scenery.

The latter end their day back in Talkeetna, sitting down to dinner and drinks. The former are just starting a long, two-week to 20-day trudge along a ski- and snowshoe-packed trail that works its way, camp by camp, upward for a dozen miles along the Kahiltna and then around the rocky face of Windy Corner to 14,200 feet.

At this elevation, the environment fundamentally changes. Below 14,200 feet, climbers are exposed to, and killed by, crevasse falls and rock slides. Above 14,200, greater danger looms. It's here that another community forms around a National Park Service ranger base and medical camp, where mountaineers prepare for the serious climbing ahead.

Rescuers stationed here hang out hoping nothing goes wrong. Usually something does: Above 14,200 feet, climbers will find no compassion for human failings.

Forty-nine-year-old Steffen Machulka from Germany went after a runaway backpack on a relatively shallow slope near 16,200 feet on the mountain May 18, 2012. He stumbled, as people are prone to do, fell and started sliding after the backpack. The slide took him over a ledge and he fell more than 1,000 feet to the Peters Glacier below.

Machulka became the first casualty of the 2012 season, but he would not be the last. Just days later, a Finnish skier descending the Orient Express fell for reasons unknown and tumbled 2,000 feet to his death.

Almost exactly a year later, 59-year-old German Klaus Bielstein became the first climber to perish on McKinley during the 2013 season when he suffered a heart attack at about 13,500 feet.

The high mountain is an unforgiving place, but that does not stop people from coming. For some, reaching the summit of the continent's tallest peak is a once-in-a-lifetime quest just to say they did it. For others, there is simply the opportunity to challenge themselves against one of the last great wildernesses and one of the most extreme environments on the globe. Few can afford to go into space, but they can find a similar adventure on a mountain with an environment almost as hostile at times.

About 1,200 per year take on the challenge these days.

The National Park Service reported about 250 of them were on the mountain last week strung out between Kahiltna base camp and high camp at 17,200 feet. More than 900 so far have registered to climb. That number will continue to grow.

Climbing season only lasts from May until July, and to date it's been plagued by colder-than-usual weather and lots of snow. Only five climbers so far have reached Mount McKinley's summit, and they were a team of parachute rescuers -- the elite 212th Rescue Squadron of Alaska's Air National Guard, stationed at Joint Base Elmendorf-Richardson in Anchorage. Trained to rescue downed pilots in combat, the men of the 212th are considered the best of the best at mountain rescue anywhere in the north. They don't climb McKinley just for the adventure. They do it for the training, too.

Contact Craig Medred at craig(at)alaskadispatch.com