Spreading out for 89,000 acres to the north of Highway 4, this protected parkland (866/382-5537, www.vallescaldera.gov) is a series of vast green valleys, rimmed by the edges of a volcano that collapsed into a huge bowl millennia ago. At the center is rounded Redondo Peak (11,254 feet).

It was originally a private ranch—the U.S. government bought the land in 2000 and then created an experimental structure to manage the new preserve, with the goal of making the area self-sustaining, independent of government funds. To this end, use fees are high (starting at $10 per person), and you must make reservations at least 24 hours ahead of time online, as there are restrictions on how many people may enter the park each day.

The reward is a hike through land that feels utterly untouched, where you might see herds of elk grazing and eagles winging across the huge dome of the sky. Hiking is best June–September, but the park is open in winter for cross-country skiing, and there are limited elk-hunting and fishing seasons.

In addition to exploring on your own, a full roster of guided activities is available: group day hikes, full-moon snowshoeing and sleigh rides, overnight winter yurt camping, tracking classes, horseback riding, and more.

If you haven’t planned for a stop here, you can still use the Coyote Call Trail, a 3.5-mile loop off the south side of Highway 4, and the Valle Grande Trail (two miles round-trip), off the north, without reservations.

Past Valles Caldera, Highway 4 goes into Bandelier National Monument.

If you’re carrying on to Santa Fe, go through White Rock and join Highway 502, which leads through Pojoaque to U.S. 285, which then goes south to the capital.