California is packed with hidden underground worlds just waiting to be explored.
We’re talking about massive caves, twisting lava tubes you can hike straight through, and secret sea caves once used by smugglers.
Some of these caves are tucked beneath towering redwoods, others are hidden in the middle of the desert, and a few even require a boat ride just to reach the entrance.
Want to see sparkling crystal formations, giant caverns, and tunnels made by molten lava?
This ultimate California caves and caverns road trip will take you to the wildest, most jaw-dropping underground spots in the state—so get ready to explore!
1. Lake Shasta Caverns, Lakehead
Lake Shasta Caverns is a mind-blowing cave hidden inside the limestone cliffs of Shasta Lake in Northern California.
It’s packed with twisting passageways, towering stalactites, and wild rock formations that look like something out of a sci-fi movie.
To get there, you’ll hop on a catamaran across the lake, then take a steep bus ride up the mountainside before finally stepping into the cool caves that have been forming for approximately 250 million years.
Inside, you’ll see massive flowstones, delicate soda straws, and a cavern room so big it’s called the Cathedral Room—all lit up to show off every crazy shape and shadow.
2. Subway Cave, Lassen National Forest
If you’ve ever wanted to walk through a pitch-black lava tube formed by a volcanic explosion, Subway Cave in Lassen National Forest is your chance.
This massive, 1,300-foot-long tunnel was carved by molten lava around 20,000 years ago, and today, you can hike straight through it—just don’t forget a flashlight because it’s completely dark inside.
The cave’s floor is rough and rippled from the cooling lava, the ceiling has deep cracks from trapped gas bubbles, and the whole place stays a chilly 46°F year-round, making it the perfect escape on a hot summer day.
Please note that the cave closes over winter and is typically open from late April through October.
3. Black Chasm Cavern, Volcano
Located in the tiny Gold Rush town of Volcano, Black Chasm Cavern looks like a glittering underground palace, thanks to its insanely rare and delicate crystal formations called helictites.
These twisted, gravity-defying minerals sprout from the walls and ceilings in wild, tangled shapes, making this cave look more like an art exhibit than a natural wonder.
A wooden walkway winds through the cavern, leading you past deep blue underground lakes and towering rock formations.
The guides will also reveal fun facts about the cave’s discovery and the gold miners who totally missed this hidden gem right under their feet.
4. California Cavern State Historic Landmark
California Cavern State Historic Landmark was one of the first recorded caves in California, discovered by Joseph Taylor back in 1850, and became the state’s first show cave open for public tours.
Gold miners were the first to stumble into its massive chambers, but today, you can wander through winding passageways and squeeze into hidden rooms.
You can also explore the ‘Jungle Room,’ known for its dense clusters of stalactites and stalagmites that resemble an underground forest.
With sparkling calcite formations hanging from the ceiling and walls that shimmer like they’ve been dusted with gold (spoiler: it’s not actual gold, but still cool), this cavern has been wowing visitors for over 170 years.
Please note: the cavern closes over winter and usually reopens in late March.
5. Mercer Caverns, Murphys
Mercer Caverns in the charming town of Murphys feels like a maze of tight passageways, towering stalactites, and some of the craziest cave formations in California.
It was actually discovered in 1885 by a gold prospector named Walter J. Mercer (spoiler: he found a cave instead).
This underground wonder is packed with needle-thin aragonite crystals, rippling flowstones, showcasing stunning natural formations formed over millions of years.
The guided tour takes you down approximately 160 feet below the surface via a steep staircase, so get ready for some serious leg day—but the jaw-dropping sights are 100% worth it.
6. Moaning Cavern Adventure Park
Moaning Cavern Adventure Park is home to the largest single-chamber cave in California, big enough to fit the Statue of Liberty inside—yeah, it’s that massive.
It got its name from the eerie, moaning sounds that echoed from the entrance before it was fully explored, thanks to water dripping into flowstone formations.
You can take the classic staircase tour deep into the cavern or, if you’re feeling extra daring, make your way 165 feet down into the darkness via the Spiral Tour’s 100-foot spiral staircase like a true cave explorer.
7. Pinnacles National Park Caves
The caves at Pinnacles National Park aren’t your typical underground caverns—they’re actually talus caves, formed when massive boulders tumbled into narrow canyons, creating dark, twisting passageways.
You’ll scramble over rocks and squeeze through tight spots—all while keeping an eye out for the park’s real VIPs—endangered Townsend’s big-eared bats that call these caves home.
With two main caves to explore, Bear Gulch (short and family-friendly) and Balconies (longer with a bit more adventure), this is the perfect spot for anyone who loves hiking and epic rock formations.
Please note: The caves have seasonal closures to protect the bats. Bear Gulch Cave is open most of the year but fully closes in spring and fall.
Balconies Cave is usually open year-round but may close due to flooding after heavy rain—be sure to check online before your visit!
8. Boyden Cavern, Kings Canyon National Park
Boyden Cavern sits right beneath the towering cliffs of Kings Canyon, hiding a stunning underground world just steps from the highway.
Inside, you’ll find a little bit of everything—massive flowstones, delicate stalactites, and even a rock formation called the Drapery Room that looks like rippling curtains frozen in stone.
The short but super cool guided tour takes you past the famous “Christmas Tree” flowstone and into a glittering chamber.
Please note: Boyden Cavern usually closes over winter and reopens in April.
9. Crystal Cave, Sequoia National Park
Crystal Cave in Sequoia National Park features marble walls polished smooth by ancient underground rivers and delicate formations that sparkle under the glow of lantern light.
A winding path leads you through cathedral-like chambers filled with dripping stalactites, shimmering flowstones, and eerie passageways that look straight out of a storybook.
Since this cave is tucked deep in the park, getting there involves a scenic drive through giant sequoia trees, making the adventure just as magical above ground as it is below.
Just a quick reminder that the cave usually closes over winter and reopens in the summer, and it can only be visited by a guided tour.
10. Mitchell Caverns, Essex
Mitchell Caverns in the heart of the Mojave Desert is a wild contrast—blistering heat outside, cool underground tunnels inside, packed with jagged stalactites and otherworldly rock formations.
Part of the Providence Mountains State Recreation Area, these caves were once used by Indigenous people thousands of years ago, with the Chemehuevi referring to them as ‘the eyes of the mountain’.
Today, you can only visit on a ranger-led tour, but it’s worth it—the twisting passageways and massive limestone columns make this one of California’s most unique cave adventures.
Please note that Mitchell Caverns typically closes during July and August, reopening from September through June when guided tours are available.
11. Cave of Munits, Los Angeles
Cave of Munits isn’t your typical underground cavern—it’s a massive, cathedral-like cave carved into a cliffside in the middle of Los Angeles’ wild, rugged hills.
Legend has it that this was once home to a powerful Chumash shaman, who, according to the legends, met his demise after killing a chief’s son.
Today, you can climb through its towering, open-roofed chambers and scramble up rocky ledges for some seriously epic views of the San Fernando Valley.
It’s a short but steep hike to get there, and if you’re up for a challenge, you can even keep climbing past the cave to the rocky peaks above—but fair warning, it’s not for the faint of heart!
12. Sunny Jim Cave, La Jolla
Sunny Jim Cave in La Jolla is the only sea cave in California you can walk into, thanks to a secret hand-dug tunnel hidden inside a little gift shop.
A creaky wooden staircase takes you down through the cliffside, leading to a breathtaking opening where the Pacific Ocean crashes against the rocks.
Legends say smugglers once used this cave to sneak booze into San Diego during Prohibition, though there’s little solid proof.
But today, it’s just a fun, slightly eerie spot to soak in ocean views and pretend you’re part of some secret coastal adventure.
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