This Secret Pool Is Hidden in a Cave Beneath a Famous City in Texas

You might think you know what to expect from Central Texas.

Rolling hills, wide-open skies, maybe some bluebonnets if you time it right.

But hidden beneath the surface of Georgetown lies something completely unexpected: a pristine underground pool tucked deep inside one of the best-preserved cave systems in the Lone Star State.

Walk with me as we tour the Inner Space Cavern and explore its beauty below ground.

Where the Hidden Pool Is Located

Inner Space Cavern sits right off I-35 at Exit 259, just about 30 minutes north of Austin in Georgetown.

What makes this place so special is the story of how it was found. Back in 1963, a Texas Highway Department core drilling team was testing the ground for highway construction when their drill bit suddenly dropped 26 feet into nothingness.

Imagine being that worker, realizing you’ve just punched a hole into a secret world that had been sealed off for over 10,000 years.

That unexpected void turned out to be one of the best-preserved caves in Texas, a 5-mile system that had no natural entrance to the outside world until that fateful drill broke through.

Because it was completely sealed, the cavern remained in pristine condition, untouched by humans or the elements. The cave opened to the public in 1966, and visitors have been marveling at its wonders ever since.

The underground pool is found along the guided tour routes, deep within the cavern’s winding passages.

Known as the Lake of the Moon, this stunning feature sits at the deepest point of the cave, 69 feet below the surface.

Getting there means walking through a wonderland of limestone formations, past towering flowstones, delicate soda straw stalactites, and massive columns that took hundreds of thousands of years to form.

The Lake of the Moon

The Lake of the Moon earned its name back in the mid-1960s, before humans had actually set foot on the lunar surface.

Early visitors thought the area surrounding the pool looked like what they imagined the moon would be, with its otherworldly formations and ethereal atmosphere. The name stuck, and honestly, it’s pretty fitting.

The pool itself is crystal-clear, fed by water that has been naturally filtered as it slowly passes through the limestone above.

This makes it some of the purest water you’ll find anywhere. The surface is so still and calm that it creates a perfect mirror effect, reflecting the stalactites and formations above it.

What It’s Like to See It in Person

To protect this remarkable environment, access to Inner Space Cavern is limited to guided tours only. You won’t be wandering off on your own, and that’s a good thing.

The guides are incredibly knowledgeable, sharing stories about the cave’s discovery, the science behind its formations, and the prehistoric animals whose fossils were found within.

The Adventure Tour is the most popular option, lasting about 60 to 75 minutes as you walk approximately one mile along paved and lit pathways.

It’s suitable for most ages and fitness levels, though the route includes some steep and uneven sections.

For those craving more adventure, the Hidden Passages Tour takes smaller groups through narrower corridors with flashlights, and the Wild Cave Tour offers a true spelunking experience with crawling and climbing.

Planning Your Visit

Best Time to Go

Inner Space Cavern is open year-round, making it an ideal destination no matter the season.

During scorching Texas summers, ducking underground for a 72-degree escape is pretty much heaven. And when cold snaps hit, the cave offers a cozy alternative to shivering above ground.

Weekdays tend to be quieter than weekends, especially if you avoid times when school field trips are scheduled.

The cavern’s website has a daily calendar to check for group bookings. Tours depart every 20 to 30 minutes on a first-come, first-served basis for the Adventure Tour, so you won’t need reservations unless you have a group of 20 or more.

What to Know Before You Go

Comfortable walking shoes are a must.

The pathways can be steep, wet, and uneven in spots, though handrails and floor mats help you navigate safely.

Photography is allowed, but there are a few rules. No tripods are permitted, and avoid using flash near the bats.

Yes, Inner Space Cavern is home to tri-colored bats that hibernate in certain areas. If you’re lucky, your guide will point them out, but it’s important not to disturb them.

Backpacks, food, and drinks are not allowed inside the cave, but there’s a small café at the ticket counter.

Where the Surface World Disappears

Inner Space Cavern’s Lake of the Moon is one of those Texas treasures that catches you completely off guard.

Who would expect a pristine underground pool, surrounded by ancient formations and prehistoric fossils, hiding just beneath highway traffic?

Yet there it is, waiting 69 feet below the surface, just as it has for thousands of years. This hidden oasis feels worlds away from the Texas heat above, and that’s exactly what makes it so unforgettable.