Don’t be scared off by the name. Far from hellish, Devil’s Den Spring is a subterranean slice of heaven located in Williston, Florida.

Divers and snorkelers from around the world trek here to experience the wonders of this remarkable prehistoric spring flowing below ground inside a vast dry cave.

From ground level, you might miss it altogether. The only thing visible is a fern-draped opening called a karst window that resembles a small sinkhole. It’s actually the spot where part of the cave’s soluble limestone ceiling collapsed long ago. On cool winter mornings steam rises from the hole like smoke from a chimney — or hell, as early settlers imagined. (Thus the reason for its moniker Devil’s Den).

Peer into the hole, and a breathtaking submerged world opens up, complete with pool of clear blue water some 60 feet below.

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For much of the 20th century and probably before, Devil’s Den was a secret swimming hole for nearby residents. Located in a pasture and surrounded by woods, the property was purchased in 1993 by private owners. It’s now considered a world-class diving spot and eco-destination, plus it also serves as a certified scuba diving training center. Regular swimming is not allowed.

To reach the sunken fresh-water spring, visitors make their way down a flight of narrow stone stairs and then a wooden staircase to a diving platform built inside the majestic cavern. Those who enter are often struck by the otherworldly silence punctuated only by occasional water drops.

The spring, lit by sunbeams from above, stretches more than 100 feet across the cave bottom. It’s actually part of the Floridian Aquifer, an underground river that supplies much of the state’s fresh water.

Maintaining a steady 72 degrees Fahrenheit year-round, the pristine water reaches a depth of more than 50 feet. Divers often see guppies, crappies, catfish and turtles as they explore underwater tunnels and ancient rock formations, including stalactites and fossil beds.

divers prepare to explore Devil's Den Spring Scuba divers and snorkelers prepare to explore Devil’s Den Spring from the diving platform built inside the underground cavern. (Photo: Matthewjparker/Wikimedia Commons)

In fact, Devil’s Den Spring is a treasure trove of fossils dating back to the Pleistocene Age (2.5 million to 11,000 years ago). Many were recovered in the 1960s and are now displayed at the University of Florida’s Museum of Natural History in nearby Gainesville. Among them are human bones that researchers believe could be from the late Pleistocene, as well as extinct prehistoric mammal species, including North American spectacled bear, dire wolf, ground sloth, American mastodon, southern bog lemming, saber-toothed cat and Pleistocene horse.

For visitors staying overnight or longer, Devil’s Den Spring offers a secluded campground, RV park, double-wide trailer and cabins on its 100-acre property. Nearby attractions include Cedar Lakes Woods and Gardens (a sprawling botanical garden on the property adjacent to Devil’s Den), Blue Grotto (another diving cavern two miles down the road), and Two Tails Ranch (an elephant and wildlife sanctuary also in Williston).