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Natural Bridge goes big in its 'new' cavern

Light show in the Box Canyon room
Natural Bridge Caverns
Light show in the Box Canyon room

If you grew up in San Antonio, it’s likely that you took an elementary school field trip to Natural Bridge Caverns in the Hill Country outside of Garden Ridge.

It’s been a popular show cave for decades, but right next door to it, a cavern first discovered in the 1960s finally opened up last year. And what Natural Bridge has done in Hidden Wonders made it unlike any other cave in Texas.

When you visit, you'll be greeted by cave guide Olivia. “Welcome to Hidden Wonders!" she said. "Before we get started, we’re going to go over a couple of rules.”

The first rule: like any other cave, you can’t touch the formations. And also: “There are some steep and wet sections. You will be going down more than 190 steps today,” she said. “Don’t worry; you won’t have to walk back up those stairs!”

And so we began our descent.

“Although our path will be well-lit today, I’d like to remind everyone that for millions of years this cave was in total darkness,” Olivia said.

The first room is a large one, but it’s not so long as it is deep. The formations are a sight to see, and the lighting, which Olivia changes to specifically illuminate she’s pointing out, was created to highlight each formation’s peculiarities.

Texas has a deep tradition with caves, which Natural Bridge’s Winter Prosapio said were provided in abundance.

“It's this rocky, porous area that often creates caves, and there's caves all over this part of Texas,” Prosapio said.

It’s not just the limestone rock that makes caves happen though.

“Our caves here are formed by water. And then the decoration, which is what we call the formations — those are created also by water and time and lots of minerals in the limestone,” she said.

Rainfall is absorbed by the soil, then leaches through the limestone, dissolving tiny bits of it as it goes down. When it gets to an open space — a cave — where it drips and solidifies is how and where formations are created.

For years, the Natural Bridge owners had a hunch there was another cave nearby, so they drilled four pilot holes and sent a camera down. The last hole was the payoff.

“They took four pictures, and the first three were white and the last one was black,” Prosapio said. “And they knew that meant back then that they had just found an immense room because the light from the flash couldn't reach the end of the room and come back to the film.”

They widened the hole and shimmied down a rope to discover what they now call Hidden Cavern.

“And they decided what we want to do with this cavern is we want to not just put in new lights, but really expand what people can see, because there's three really interesting spaces that we could take people through if we just had the opportunity,” she said. “So they kind of went big and expanded, nearly a football field worth of cavern.”

The Hidden Cavern tour is primarily three really large rooms, each quite different from the last. One of those rooms — the Box Canyon — lent itself towards an extensive light show experience.

“The people who lit the cave, who put the new lighting system in, they're the best in the world that came from Germany, because you have to have cavers to light a cave, because they've got to climb over things,” Prosapio said. “They have to know to be careful. They need to know not to break anything that's been spending a lot of time growing.”

The lighting is synchronized with a soundtrack composed to go with the lighting.

“That was a score created for us by Chris Thomas, who's a musician and does these kinds of things for national parks,” she said.

The cave changes from gold to blue, to green, each change in time with the music.

Back on the cave tour, Olivia had everyone sit, and put their phones away while she turned out the lights so we could find out what true darkness really looked like.

“I would encourage you to put your hands in front of your face so you can’t see your hands. Here we go, in 3-2-1,” Olivia said.

“Whew!” someone in the dark said.

You may think you know dark, but cave dark is as dark as it gets.

The last big room is what they call the "Ballroom," and it has a massive concrete floor.

“Because it has no formations, we have concerts there because we know sound is not going to have a negative impact in that space,” Prosapio said.

The most convenient part, especially for those who tire easily, is the way cave visitors ascend that considerable climb to the surface.

“We also have a conveyor system that takes you out because it's a 700-foot-climb out, which is no small thing for some of us, we have a conveyor belt that will kind of carry you back up. That increases accessibility for a lot of people,” she said.

Natural Bridge Caverns - Hidden Wonders 2023

The moving sidewalk out takes about five minutes, but if you prefer to walk, there’s a stationary walk right next to the conveyor. Prosapio said there are parts of the cave that only a small percentage of the public has seen.

“We do have a small section of that wild cave that we open for adventure tours, for people who really want to have a taste of caving, with a very knowledgeable guide in an area, as we've gone through many times before,” she said.

Natural Bridge Caverns will mark 60 years of cave tours on July 3.

Texas Public Radio is supported by contributors to the Arts & Culture News Desk including The Guillermo Nicolas & Jim Foster Art Fund, Patricia Pratchett, and the V.H. McNutt Memorial Foundation.

Jack Morgan can be reached at jack@tpr.org and on Twitter at @JackMorganii