When Mount Mazama erupted 7,700 years ago, it left a six-mile-wide, 4,000-foot-deep caldera; more than 40 caves; and an impossibly deep pool, sounding at 1,949 feet. In the summer, the rim of Crater Lake National Park’s shimmering centerpiece teems with worldwide visitors. But the park’s rugged beauty—crystalline waters, craggy basalt shoreline, and pine-timbered slopes—is best viewed in the colder months, via an epic 33-mile circumnavigation on skis.

The rim averages 44 feet of annual snowfall. In winter, you may need to plow through deep drifts and under avalanche zones as you meander through stands of gnarled whitebark pines and across pristine meadows. In spring, the trail is less challenging, allowing more time for ogling the scenery. So plan ahead for a couple of days (no need to take on the 6.5-hour record set by John Day and the Italian national ski team in the winter of 1977) in March or April, when the snow is compact, the sky is sun-filled, and the shimmering abyss reflects the view.

First, check in at Steel Visitor Center for a backcountry camping permit and route information; then stop at Rim Village, 7,100 feet elevation, where you can get a last-minute latte at the café. From there, set out on snowy Rim Drive for a clockwise journey that undulates dramatically—4,000 feet of climbing and 4,700 feet of downhill turns. Ski north past Hillman Peak and the Watchman, two hummocks that command panorama views if you climb them. Spy Wizard Island and look for the Old Man of the Lake, a log that’s been floating upright for a century. Pitch your camp on the north side of the lake, at least 100 feet from the rim, in an area sheltered from the wind and safe from avalanches. And if you’re up for it, cruise south on rolling hills and zip out to Cloud Cap Overlook, a short junket to the high point on the rim, at 8,065 feet elevation.

On day two, route-finding becomes trickier as the trail dives into thick woods and you lose sight of the lake for stretches of time. But Mount Scott, an andesite lava cone, makes a righteous, optional ski mountaineering objective at 8,832 feet. On the final leg of the tour, just coast westward back to Rim Village, where steaming bowls of soup await.