FRESNO, Calif. (KFSN) -- The intense Valley heat isn't a problem if you're able to go underground to cool off.
That's what we did in this week's Hidden Adventure.
Boyden Cavern is a destination many people in the Valley don't realize is so close and yet feels like a faraway land once you're inside.
The grandeur of Kings Canyon National Park is impressive.
But soaking in the sights 77 miles from Fresno isn't enough for some.
Boyden Cavern rewards those willing to take a five-minute hike "up" to the entrance.
You can enjoy a view of the south fork of the Kings River.
The payoff though is worth it. Cave Explorer Devin Benavides said, "Yeah, definitely the way up was challenging. It was definitely worth the brutality of it, though. Absolutely."
Tour guide Stella Baker took us inside, and we have Putnam Boyden to thank for our Hidden Adventure.
Baker explained, "He was a logger at Hume Lake and he came up here in 1907 looking for the cavern expressly."
Boyden filed a mining claim, didn't find any gold but discovered a gem of a hideaway.
You need to duck and twist your way through some of the passages, but cavern illumination and flashlights reveal remarkable formations along the marble walls.
Baker explained to the tour group, "When you consider everything's growing one drop of water at a time, it takes thousands of years for this to happen."
Stalactites grouped together created what is referred to as "upside-down city."
Baker said, "I call it Seattle because of the Space Needle right there. Oh, wow."
At one point, all of the lights are shut off.
Kira Heberlein of Clovis admitted, "That was a little disorienting. You forget if you're standing up straight and you're like, oh my God, how do people do this?"
Sometimes it's so dark, kids may think they're walking through a haunted house.
You do see a formation that resembles a skull.
But this is a fun stroll where calcite has helped create cave curtains, cave bacon, even a wedding cake.
Maria Baker said, "There's a lot of food-based names. I think cavers are a very hungry group so you could see a stack of pancakes, maybe a little bacon to go along with that."
12-year-old Audrey Yang wished she brought a flashlight but still was able to make out her favorites.
Yang said, "I liked the Christmas tree, the wedding cake and when they did the blackout, it's kind of fun."
The so-called Christmas tree is estimated to be 70,000 years old. Stella recalls one family that snapped a memorable photo. "They stood in front of here and they were going to use it as their Christmas card and I thought, brilliant!"
Every turn brings something new into view.
Boyden Cavern is literally the coolest place in the park. Inside, it stays 55 degrees year-round, and that's important on a hot summer day.
Benavides said, "The gentleman who first discovered it back in the early 1900's definitely had the right idea. Sort of air conditioning before air conditioning."
Some people who come to Kings Canyon are surprised to find their options go beyond fishing, hiking and camping.
Baker said, "We even get a lot of locals who didn't know this part of the forest was here, much less that we have a cavern here."
You can leave the same way you came in or take the "wild cave" exit and make your through a shallow creek bed.
This year, though the path is dry due to our drought conditions, visitors didn't seem to mind.
Heberlein said, "That was really fun. It was dim and you got to experience what the pioneers did."
Boyden Cavern tours are now running at full capacity.
If you are fully vaccinated, you don't have to wear a mask during the tour.
For ticket information, just visit their website.