Pluto's Cave can reach 1,200 feet into the ground.

Part of the adventure in luring your friends out to the high desert terrain in Northern California, where a valley floor spills from the northern backside of Mount Shasta, is that precious moment when they look at you as though you’ve led them into danger. 

Having discovered Pluto’s Cave from a map, I was prepared for some sagebrush whacking. What I wasn’t prepared for was that reaching the trailhead required navigating a maze of dusty roads. The cave is considered an easy hike — no serious spelunking experience necessary — and located less than 20 minutes from Interstate 5. 

Pluto’s Cave is a partially collapsed lava tube in the Klamath National Forest. The cave’s opening is estimated to be 10 feet high and 20 feet wide, with a depth of some 1,200 feet into the Earth’s abyss. 

The hike to Pluto's Cave in Klamath National Forest requires meandering through sagebrush.

For a torrid summer day, a venture into the cool underbelly of Shasta was an ideal pursuit to beat the heat. The cave keeps a cool 50 degrees, regardless of what’s happening outside. I plotted the coordinates via Google Maps and set north. This would prove to be the first mistake. 

Splitting from I-5 in the town of Weed is Highway 97. Part of the Volcanic Legacy Scenic Byway, the route earns its name for how it carves along the Cascade Range, where volcanoes are numerous. Charred residue from the 2014 Boles Fire was visible during the highway’s initial 10 miles.

We cut off from the highway and, per Google Maps’ insistence, I guided us through a rural residential area. It was the type of outback neighborhood that doesn’t appear on Google’s Street View. Front gates have convincing signs that trespassing would be a fool’s errand, and no one in their right mind would think to canvas this outpost to hawk some solar energy panels. 

Scambling down to the entrance of Pluto's Cave in the Klamath National Forest. Mount Shasta viewed in the background. 

Abandoned plastic tarps caught in the brush fluttered with the valley wind as my Prius — truly the worst vehicle for dodging boulders on this rugged terrain, a second mistake — skidded and scraped until reaching the end of my digital directions.

Using meager cell service, we called our friends in the other car, which we hoped was trailing us. However, we saw no dust getting kicked up from another vehicle as we peered over the flat, rustic residences. When we finally managed to connect with them, we learned that they were at the proper trailhead and we were at an unnecessary offshoot. 

Google Maps led us astray and directed us through a neighborhood that should receive the bare minimum of looky-loos. 

The mouth of Pluto's Cave in the Klamath National Forest.

The minor mishap inspires the first suggestion for hiking Pluto’s Cave: if using Google Maps, make sure you set coordinates for “Pluto's Cave Parking” in Montague, California. Don’t rely on Google getting this exact coordination automatically correct, and double-check where it’s leading you. It’ll save time and countless chafes underneath a low-bearing sedan.  

Once the gang was reunited, we passed through junipers and scorched pine trees as we meandered an unclear path toward the mouth of the cave. 

Close-toed shoes are required to climb over the jagged boulders. A headlamp is also suggested. 

A man named Nelson Cash first stumbled upon Pluto’s Cave while seeking his stray cattle in the spring of 1863, according to a 19th-century book on Siskiyou County by Harry Laurenz Wells. The cave’s vast dimensions distinguished it as a unique landmark and, as the book explains, the interior of the cave is shielded from time.  

“The walls within are very dry, the usual dampness of a cavern being absent, thus contributing to the preservation of objects deposited there,” Wells wrote in 1881.

The first section of Pluto's Cave, where remnants of a fire pit remain.

We stepped past endless sagebrush until coming upon a large opening some 10 feet beneath the valley. There were two mouths for caves. We first went to our left and found a fire pit just 25 yards into the opening. Not a very deep cave. And the dank smell was haunting. Spray painted eyes on the cave walls followed us as we returned to the opening to try the other direction. 

After ducking under a low-hanging cave ceiling that led into an exposed area, we found the entrance to Pluto’s Cave concealed behind camouflaging green shrubbery. The rim of the cave was vast — the size of an IMAX theater screen — while the floor was covered in jagged boulders. 

There was light visible from the back, which propelled us forward as we gasped in appreciation. We hobbled over rocks and soon came upon an opening in the cave’s ceiling that allowed light to pour in. Dust particles floated in the sunlight. The floor was now sand, and easy to traverse as we passed by this extraordinary opening. 

A section of fallen ceiling inside Pluto's Cave reveals a heavenly light. 

Sunlight soon became scant the further we pushed into the belly of Pluto’s Cave. We became wrapped in darkness, and as we started rock climbing, it required getting down on all fours. We soon realized our latest and third mistake: bring a headlamp. Like a pack of novice adventurers, we were spelunking using our iPhones. Switching off casting a light on one another as we burrowed deeper into the darkness, we laughed at such a rookie move. 

Each caver has their own capacity for adventure, and soon the numbers began to dwindle the deeper we climbed into the cave. Friends peeled off and went back to the cave’s lighted area as conditions became more treacherous. Eventually, only three of us remained as we tried to find the point of no return. We squeezed between rocks, ducked under fallen boulders and eventually found our limit. 

Before we decided to climb back out, the three of us turned off our lights and sat in the darkness for a few minutes. It was pure black. There was no difference when I opened or closed my eyes. The sound was muted, besides a careful reshuffling of feet, and the air was cool.

Light begins to wane as you move farther into the depths of Pluto's Cave.

Not a lick of light could reach this point of Pluto’s Cave. Even after traveling more than 93,000,000 miles from the sun, the might of light could not reach this depth. But you know who did? A few jabronis who parked on the wrong street, traveled the backroads by Prius and failed to pack a single headlamp for spelunking. 

We emerged from Pluto’s Cave feeling victorious if not humbled by our lack of preparation. Perhaps our error will become your gain if you decide to find the cave and follow the darkness until the end. 

Silas Valentino is SFGATE's Travel Editor. He was born in Bakersfield and raised in Marin County. He covered the New York City music scene for The Village Voice before returning west to report for the Point Reyes Light. Recently, he contributed to the launch of a monthly lifestyle magazine called PUNCH that focuses on the Peninsula. Outside of reading, writing and storytelling, Silas values his family (including eight nieces and nephews) and exploring the state. He lives with his girlfriend above a wine shop in Cole Valley. Email: silas.valentino@sfgate.com