Inyo Craters Trail

The Inyo Craters Trail is one of the most fascinating short hikes in Mammoth Lakes, California — a 1.5-mile loop through Jeffrey pine forest that leads to a pair of massive volcanic explosion craters, each roughly 600 feet across and 100-200 feet deep, with small turquoise ponds shimmering at the bottom. Formed by violent phreatic (steam) eruptions just 500-600 years ago, the Inyo Craters are among the youngest volcanic features in the continental United States — a reminder that the Eastern Sierra sits atop one of North America's most geologically active regions.

At barely a mile and a half with minimal elevation gain, it's an easy walk with an outsized payoff. Kids will love the sheer scale of the craters; adults will love the geology.

The Trail

• Distance: 1.51-mile loop
• Elevation gain: ~250 ft
• Difficulty: Easy — good for all skill levels
• Route type: Loop
• Surface: Packed dirt, some rocky sections
• Time: 45 minutes to 1 hour at an easy pace

The trail begins at the parking area and climbs gently through a fragrant Jeffrey pine forest (sniff the bark — Jeffrey pines smell like butterscotch or vanilla). After a short ascent, the first crater comes into view. The trail continues to a second, slightly larger crater a few hundred feet north.

Both craters are ringed with railings and viewpoints — you're not descending into them, but the views from the rim looking down at the pond floor are dramatic and unlike anything else you'll see in the Sierra.

The Craters

Each crater is:

• ~600 feet across at the rim
• 100–200 feet deep to the floor
• Home to a small pond at the bottom, often a striking turquoise-green color from mineral content
• Ringed by exposed volcanic rock and pumice deposits
• Roughly 550-600 years old — formed around the year 1400-1500 CE

There's actually a third crater further to the north on top of Deer Mountain, accessible via a longer connecting trail if you want to extend the hike.

The Geology

The Inyo Craters were created by phreatic eruptions — explosive events that happen when magma rising through the crust encounters groundwater. The water flashes to steam, blowing a massive hole in the ground. Unlike typical volcanic eruptions, phreatic eruptions produce more crater than lava.

The craters are part of the Inyo-Mono Craters chain — a line of volcanic vents that stretches ~25 miles north to Mono Lake, all fed by the same magma system beneath the region. This chain is:

• One of the youngest volcanic features in the continental US
• Aligned with the Earthquake Fault just to the southwest (which we covered separately)
• Part of the broader Long Valley Caldera volcanic complex — a supervolcanic region that erupted catastrophically 760,000 years ago
• Still actively monitored by the USGS for signs of renewed activity

Geologists consider the entire Long Valley/Inyo-Mono system to be dormant, not extinct — future eruptions are possible on human timescales.

What to Bring

• Water — even a short hike at 8,000+ feet is dehydrating
• Sun protection — hat, sunscreen, sunglasses at altitude
• Sturdy walking shoes — trail is rocky in sections
• Camera — the crater ponds photograph beautifully, especially in morning light
• A curious kid or geology-nerd friend — this is one of the most accessible geology field trips in the Sierra
• Bug spray in summer

Seasonal Guide

• Summer (June–September): Prime season — dry trail, warm temps, full access
• Fall (October): Beautiful with aspen color nearby, cooler temps, fewer crowds
• Winter (November–April): Trailhead road typically closed by snow — but the trail becomes a popular snowshoeing route if you can access it. Check current road status with the Mammoth Lakes Welcome Center.
• Spring (May): Depending on snowpack, trail may still be inaccessible or muddy through late spring

Practical Info

• Location: Off Mammoth Scenic Loop road, Mammoth Lakes, CA (accessed via a short unpaved forest road)
• Coordinates: 37.68897, -119.00562
• Land manager: Inyo National Forest / USDA Forest Service
• Fees: Free — no permit required
• Parking: Small dirt lot at the trailhead
• Restrooms: Vault toilets on-site
• Dogs: Welcome on leash
• Accessibility: Trail is dirt and includes some short climbs — not fully ADA-accessible
• Cell service: Limited — download offline maps before going
• Road access: The last stretch is an unpaved forest road — passable in most vehicles when dry but rough after storms

Safety Notes

• Do not descend into the craters — the walls are unstable and the ponds are cold, deep, and potentially contain toxic gases from ongoing volcanic activity
• Stay behind railings at viewpoints
• Signs specifically warn against biking or descending inside — take them seriously

Pair It With

The Inyo Craters Trail is best combined with other Mammoth Lakes geological and outdoor highlights:

• Earthquake Fault Trail — another short geological wonder nearby (see separate write-up)
• Devils Postpile National Monument — extraordinary columnar basalt formations
• Rainbow Falls — 100-foot waterfall from Devils Postpile
• Hot Creek Geological Site — active hot springs and steam vents
• Mono Lake — surreal saltwater lake 30 min north
• Mammoth Mountain gondola — ride to 11,053 ft for panoramic views
• Mammoth Lakes Basin — Twin Lakes, Lake Mary, Horseshoe Lake for water and hiking
• Convict Lake — dramatic alpine lake 20 min south

Why It's Worth the Stop

For a hike that takes less than an hour and requires almost no effort, the Inyo Craters Trail delivers something genuinely rare: a face-to-face look at recent volcanic activity that most people don't associate with the Sierra Nevada. The craters look almost impossibly out-of-place in the middle of a peaceful pine forest — which is exactly what makes them so memorable.

Paired with the Earthquake Fault Trail (another short geology stop just down the road), you can get a fascinating introduction to Eastern Sierra volcanic history in a single afternoon.