Florida’s ancient warm spring hides a big mystery. Here’s what to know

SARASOTA COUNTY, Fla. – Tucked away in southwest Florida, visitors can find prehistoric warm springs — the only one in the state.

This massive pool (fittingly dubbed “Warm Mineral Springs”) was formed within a deep sinkhole in North Port, and it’s a popular place for locals to frequent.

However, newcomers are likely to be surprised by the strong, sulfurous stench that the springs emit.

As the name implies, Warm Mineral Springs hosts over 50 different kinds of minerals in its waters, including sulfur, magnesium and potassium.

But for many, the mineral-induced odor is worth enduring.

“A lot of people that go to the springs, they seek it out because they believe the springs help with health and well-being...” said Kimberly Lencki with the city’s parks and recreation department. “Those (minerals) are rumored to have healing powers.”

These beliefs play into the spring’s reputation as “The Original Fountain of Youth,” though there are plenty of other attractions that make similar claims.

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Beyond that, the springs stay at roughly 85°F year-round, making them a great place to hang out when temperatures get too extreme.

This isn’t anything new, either. According to geological experts, the warm springs have been used by humans for thousands of years.

While the edges of the springs are only a few feet deep, the floor of the spring has a steep dropoff, eventually stretching to well over 200 feet from surface to bottom.

The U.S. Geological Society reports that the sinkhole formed over 12,000 years ago, and plenty of evidence has been found to support that claim.

In fact, plenty of ancient artifacts have been uncovered from the springs and beneath the park.

“During exploratory dives in the 1950s, the remains of a prehistoric hunter and seven other humans were discovered in a very well preserved state,” the city’s website reads. “Similarly, evidence of several creatures have been extracted from the spring, including saber tooth tigers, giant sloths, tortoises, and even camels.”

But what exactly keeps the springs so warm?

Well, that’s the big mystery.

Researchers in the 1970s discovered that there were two major hot water vents at the bottom of the spring’s north wall, which feed in water to the spring at around 100°F. Meanwhile, there are also nine cooler water vents that measure close to 70°F.

These various vents help to moderate the water temperature in the springs, keeping it nice and warm for guests. But researchers have yet to figure out how the water from those hot-water vents got so... hot.

Florida’s springs are typically formed from rainwater, which forms underground cavities and is eventually pushed out through openings in the ground.

And hot springs usually rely on volcanic activity to stay heated, but Florida doesn’t actually have any volcanoes (or at least none that have been discovered).

So then where is all of the springs’ hot water coming from?

One theory that researchers have posited is that seawater could be circulating below the Florida Platform from the Gulf of Mexico and the Atlantic Ocean.

At depths of 3,000 feet, the seawater may be heated geothermally before making its way through fractures in the platform’s overlying carbonate rock, ultimately getting pushed to the surface through springs like this one.

Other theories suggest that it could be seawater that had been trapped deep beneath sediments millions of years ago. Or that there exist “hot spot” anomalies where highly mineralized water is heated before being pushed into the Warm Mineral Spring.

Regardless of the truth, the springs are still available for anyone who wants to pay them a visit.

However, many of the buildings surrounding the park — including a beauty spa and eatery — are now defunct, having been damaged in major storms over the past few years.

“There was a hurricane that had damaged some of the buildings, and then (Hurricane) Ian came along, and they condemned the buildings,” Lencki explained.

But now, the city commission is working to restore the historic buildings at Warm Mineral Springs Park and figure out how to flood-proof them.

“We’re gonna restore some of the admission buildings and a complete hybrid renovation to the spa building that’s in there,” Lencki added. “They’re really converting it into an open-air pavilion.”

No official timeline has been set yet for when these renovations can be expected, though visitors can still make use of the springs themselves.

Admission fees into the park are as follows:

For more information on the park, visit the city’s website here.

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