WANAKA, New Zealand -- From the bottom, they look like butterflies, dropping soundlessly into the halfpipe and soaring high above its walls, spinning and flipping, flashes of color cascading over the whiteness. It's only after they skid to a stop and lift their bug-eyed goggles that you see the dreadlocks and soul patches, the Rockstar and Monster energy-drink logos, the tie-dye slickers and the ubiquitous ear buds.

Snowboarders remain locked in their heads as they compete to their personal soundtracks. Shredders are big on lifestyle and community, but on this beautiful and remote halfpipe, they are focused and withdrawn.

Every August, the world's best snowboarders come to work on big-air and physics-defying tricks in this tiny town hidden by mountains and surrounded by sheep. The athletes flock here for one reason: Wanaka has the only Olympic-size halfpipe open anywhere in the world at that time of year.

That means, especially heading into an Olympic year, Wanaka becomes a ground zero of aerial somersaults and 360-degree flips that is unlike anything else on the planet.

''We're a community, and there's a lot of support, no matter what your country,'' said Gretchen Bleiler, who won a silver medal for the United States at the 2006 Turin Games. ''But I'm not going to lie: there's a lot more intensity than usual.''

Days begin in the predawn darkness with athletes boarding vans for the one-hour ride up the mountain.

By noon, they are back in town and in the gym, keenly aware that the friends they are training with are also their competitors.

''It's like 'Groundhog Day,' '' said J. J. Thomas, a United States bronze medalist in 2002 at the Salt Lake Games. ''We do the same thing over and over.''

But in Wanaka, the days are broken up with field trips to settings so stunning they belong in a snow globe. It's a place for camaraderie, where riders from Norway and Russia, Spain and Japan share a playground in the afternoon and, often, a Speight's beer at night in the local pubs.

But it is also a place of fierce competition and heightened tension. The Winter Olympics, after all, are coming in February, and there are more exceptional halfpipe riders than there are spots in Sochi, Russia.

For all the natural beauty, the halfpipe is clearly the main attraction. It's where the freestyle creed of all fun and no fear is exposed as a lie. It's where an over-rotated hip or turned-out foot can scramble your brains or compress your spine.

When the pipe gets noisy, everyone here knows it means something went terribly wrong. Crashes occurred most mornings: shoulders were separated, bruises counted and stitches pulled through. Sometimes, it was much worse.

One morning, with the sunshine lending the mountain a rouge halo and fresh snow plumped into what looked like a comfortable pillow, the halfpipe got loud. It began with a collective groan and sickening thwack as Luke Mitrani, an American, fell 40 feet from the sky and landed square...