We awoke before dawn. The wind on the dune crest had died ... If at all possible, land on the sunny side of a sand dune; the shady side usually has downdrafts, so you just drop like a stone.

They're a bit elusive, so consider visiting near dawn or dusk to spot them zipping ... Spend Some Time In Great Sand Dunes National Park At less than one mile long, the hike to Zapata Falls ...

This story appears in the June 2011 issue of National Geographic magazine. At dawn, three weeks before the winter solstice, the last tendrils of fog curled gray against the pinking sky over a sand ...