Volcanoes, Geysers, & Hot Springs

With its regal mountain majesty and alpine hush, it’s hard to imagine that Mammoth Lakes is situated on the edge of an ancient volcanic caldera. Here, some 760,000 years ago, a massive volcano exploded, leaving behind the relatively flat basin now cradling Mammoth Lakes. A wonderful byproduct of this fiery past is the region’s network of natural hot springs. Many of these bubbling hot tubs, some developed for safe dipping, are concentrated between Bridgeport and Mammoth Lakes. Stop by the Mammoth Lakes Welcome Center (just west of U.S. 395 at 2510 Main St.) for locations and directions. Also check on access; routes may be closed in winter.

Here are three natural hot springs in the region, all safe for soaking.

Benton Hot Springs: In the almost-ghost-town of Benton, relax under shady cottonwoods in one of nine tubs filled with ultra-pure spring water. Each tub has hot and cold taps so you can easily control the water temperature. The springs are on the grounds of the Old House and Inn at Benton Springs, where you can book a stay in a late-1800s ranch house or a 1940s-era lodge room. Springs are located on State Route 120 about an hour's drive northeast of Mammoth Lakes; reservations suggested.

Travertine Hot Springs: Get sweeping views of the east side of the Sierra Nevada while you soak in this natural hot spring. You can pitch a tent nearby, though not adjacent to the springs. Travertine Hot Springs is easily accessed off U.S. 395 just south of Bridgeport (about an hour's drive north of Mammoth Lakes).

Keough Hot Springs: First opened as a medicinal and health retreat in 1919 (the water is said to contain 27 different minerals), these springs are still a great place to soak and relax. There's camping on site, and lodging options include several tricked-up cabin tents, some with queen-size beds and down comforters. From Mammoth Lakes, drive south about 1 hour on U.S. 395 to Keogh Hot Springs Road. Closed Tuesdays.

Nestled in a notch of the High Sierra about an hour’s drive southeast of Lake Tahoe, mineral springs bubble up from the earth, a testament to the geologic and geothermal forces that have shaped this landscape. This state park, just west of the quiet mountain town of Markleeville, may or may not have been discovered in 1844 by John C. Fremont, the explorer credited with first sighting Lake Tahoe. Historians haven’t settled that debate. But no one disagrees that since the 1850s, people have flocked to “take the cure” in these restorative waters.

The park’s pools are fed from six different springs containing low amounts of sulfur. That means you won’t notice the strong “rotten-egg” smell of many hot spring pools. The water emerges from underground at a scalding 148°F/64°C, but it’s cooled down before it’s piped into the park’s two concrete pools—one for soaking at a safe 103°F/39°C, the other a pleasant temperature for swimming and splashing.

The pools are open most of the year (hours may vary during the off-season/winter period, September through May, so call ahead; 530/694-2249). The state park also has a 76-site campground and hiking trails, some easy scrambles for the kids (don’t miss the walk to the waterfall along Hot Springs Creek), as well as longer treks into surrounding alpine regions.

A surreal landscape sculpted by molten earth, Lava Beds National Monument contains volcanic tablelands punctuated by cinder cones, pit craters, and spatter cones, plus more than 700 caves. These strange features were formed when the outer edges of flowing lava began to cool, forming tubes. When molten lava stopped flowing, hardened tubes were left behind.

Though the scene can seem barren and desolate, look closer. The scrabbly earth and dark rocks of the rugged lava flows are dotted with sagebrush, mountain mahogany, and Western junipers, creating habitat for mule deer, pronghorn antelope, rabbits, and bird species, including bald eagles. Bring binoculars and see what you can spy, especially early mornings and evenings.

You’ll also want to bring a good headlamp or flashlight—and a jacket—for exploring the lava tubes. In summer, this part of California can get pretty toasty, with daytime temperatures of 100°F/37°C or more. But inside the lava tubes, it’s remarkably cool; you may even find year-round ice.

You can explore the tubes on your own (no spelunking experience is needed, and kids flip out at the thrill of entering these mysterious formations). And although you won’t cover much ground, the trek can be a workout as you duck, twist, and even crawl through natural tight squeezes. It’s easy to see how these caves were used as hideouts during the Modoc War in 1872-73, the only fight against Native Americans in California, in which Native Americans fought U.S. Army troops in defence of their homelands.

Some two dozen tubes are open for exploring along Cave Loop Road, near the visitor centre. Most of the park’s caves are rated for difficulty, and first-time explorers should start with the Hopkins Chocolate Cave (1,405 feet/428 meters) or Blue Grotto Cave (1,541 feet/469 meters). For the ultimate challenge, consider entering the remarkable Catacombs Cave, one of the park’s longest and most complex, with a total length of 6,903 feet/2,104 meters.

The truth is that the name Fossil Falls is a bit of a misnomer. After all, there are neither fossils nor a waterfall here. But a walk through these polished lava formations about 36 miles/58 kilometers northwest of the desert city of Ridgecrest is a highlight of any drive along Highway 395.

This remarkable site was formed by the interaction of rushing water from the Owens River (which in wetter prehistoric times flowed at a much higher rate) with lava that poured from nearby volcanoes as recently as 20,000 years ago. The result is this surreal, convoluted chasm of shiny, sculpted black lava. A short trail leads to the falls, which you can observe from above or, for a closer look, follow a trail to carefully descend the falls (hold onto children’s hands as footing can be tricky).

Insider's Tip: Night skies in this remote high desert locale are also spectacular; check out the nightly celestial show from the Fossil Falls campground with 11 sites (potable water and restrooms on site), plus picnic tables and fire rings.