Nestled in the Texas foothills, just outside the city limits of Austin is Jacob’s Well, the second-largest, fully submerged cave in the state. Flowing from Cypress Creek, the cave’s entrance is 12 feet in diameter and descends nearly 14 stories underwater.
When settlers first discovered the cave around 1850, the entrance gushed water six feet into the air. The phenomenon seemed so miraculous that the settlers named the cave after a Biblical reference. In reality, the cave is an artesian aquifer, meaning it contains trapped groundwater surrounded by impermeable rock or clay that applies pressure to the water, forcing it upwards.
Due to development in the area, the cave no longer geysers water, but it’s still an impressive sight. Today, it serves as a swimming hole and includes rock outcroppings 10 to 15 feet above the water that you can jump off of. Don’t worry about hitting the bottom, though, the first section of Jacob’s Well is 23 feet straight down, before it veers off into deeper sections.
The cave is a popular exploration destination among certified cave divers. According to the Texas Standard, there are tunnels in the cave that stretch a quarter mile long and are easy to get lost in. These are not the kind of caves amateurs should be exploring.
Unless you’re certified, we suggest lounging around the surface. With water temperature averaging a cool 68 degrees, it’s a replenishing spot to spend a hot Texas afternoon. Just make sure you book a reservation. The Jacob’s Well Natural Area park staff only allow a certain number of people to swim at one time. Access to the area is free, but the cave is only open between 8 a.m. to 6 p.m. through May 1 to September 30. The restricted hours give the water time to replenish and avoid pollution.
If you want to make a day of it, consider working up a sweat on the park’s hiking trails before taking a plunge into Jacob’s Well.