Great Sand Dunes National Park in One Day
Arrive early in the day during the summer so you can hike up to High Dune and get a view of the entire dune field. Round-trip, the walk itself should take about 1½ to 2 hours (plus time to jump off or slide down the dunes). In the afternoon, hop into the car and head to Zapata Falls, hike on the short-and-shady Montville Nature Trail, or head for the longer Mosca Pass Trail, which follows a small creek through cool aspens and evergreens to one of the lower mountain passes. You can build sand castles only by the creek because you need water.
In the spring and early summer or fall, when the temperatures are cooler, first walk up to the High Dune to enjoy the view. If you're game to hike farther, head to Star Dune for a picnic lunch. Hike down the eastern ridge to Medano Creek, then head to the western end of the park to explore the sand sheet, grasslands, and wetlands.