Last updated on November 23rd, 2020.

Hot Springs of Florida

Florida is home to thousands of beautiful, natural springs. Few know this, but some of those are natural hot springs.

Due to the depth of their spring water sources, the spring water is heated by the earth’s core. However, these hot springs are not like others you may be familiar with.

Florida’s hot springs are not as hot, or as intense, as those found near active volcanic regions. Scientists don’t fully understand the geothermal heat source of Florida’s hot springs, but they know it’s not volcanic. Instead, the water is geothermally warmed from the Earth’s core, as groundwater interacts with the hot rocks deep inside the Earth’s crust.

Florida’s hot springs are very unusual. Among thousands of springs, only a few are hot springs. Almost all of the others remain a chilly 72 degrees year ‘round. They’re warm enough to swim on warm winter days, and are refreshingly cool during steamy summers.

List of Florida’s Hot Springs

Warm Mineral Spring

Warm Mineral Spring is the only hot spring in Florida that’s open to the public. In the past it has also been known as “Warm Salt Spring”, “Salt Spring” and “Big Salt Spring”.

Although it is designated as a hot spring, that name is a bit generous. Its waters are approximately 85 degrees, which varies depending on rain conditions and water flow rates. Really, it’s more like a warm spring than a hot spring.

But, deep below the surface— approx. 200 feet— Warm Mineral Spring is a real, true hot spring in Florida. Geothermal heated water gushes from deep within the Earth at a genuinely hot 97 degrees F.

An event held at Warm Mineral Springs
A vintage photo of a swimsuit competition held at Warm Mineral Springs
Florida Hot Springs: Warm Mineral Springs
Warm Mineral Springs is one of only three known natural hot springs in Florida, and the only one with public access.

Warm Mineral Springs is an incredible place. People visit from all over the world to bathe in its mineral-rich waters.

Warm Mineral Spring is also steeped in historical significance. It’s been used for thousands of years by Native  Americans. Amazing archgeological finds, like prehistoric animals and even human remains, have been found in the spring’s depths. Since

There is speculation that Spanish conquistador Juan Ponce de León may have been mortally wounded while searching for the Warm Mineral Spring site. He died from his injuiries after being shot by a Native American’s poison-tipped arrow.

For more information, check out our guide to Warm Mineral Springs.

Little Salt Spring

Little Salt Spring is one of only three known hot springs in Florida, and one of only two located on land. It’s an important archeological site which is owned and managed by the University of Miami.

Florida Hot Spring: A Marine Archeologist Surfaces with Artifacts from Little Salt Spring
A marine archeologist surfaces with artifacts

Little Salt Spring a fascinating spring, and has been the site of amazing historical treasure finds, including rare human remains from the last ice age.

 

Incredibly, some of the remains contained brain matter, scalp and hair. This is thanks to the extremely low levels of oxygen in the water, which makes it impossible for bacteria to grow. Because of its historical, archeological and geological significance Little Salt Spring is managed as a private research site, which is not open to the public.

 

Florida History: Warm Mineral Spring Archeological Discovery
Wilburn “Sonny” Cockrell, a Florida State University archaeologist, displays a pre-historic human skull recovered from Warm Mineral Spring


Hot Mud Hole Spring

Hot Mud Spring is an amazing Florida hot spring. But unless you’re a fisherman or a scuba diver, it’s not accessible. Like Warm Mineral Spring, this spring head is deep underwater, miles offshore on the bottom of the Gulf of Mexico. Mud Hole Spring is one of approximately six known geothermal springs in Florida’s coastal waters.

Like Warm Mineral Spring, Hot Mud Spring is hot because the spring system runs deep enough to be warmed by the Earth’s geothermal core. And like Warm Mineral Spring, the underwater vent discharges hot spring water (97F) that’s unusually rich with nutrients and minerals.

Fishing and Scuba Diving

Mud Hole Spring is home to large fish, sharks, turtles and other sea life. The warm temperature and rich concentration of nutrients, minerals and microscopic life supports a thriving submarine ecosystem. It’s one of two important grazing areas in the Gulf of Mexico where loggerhead sea turtles come to forage. The other is the amazing Flower Garden Banks. Mud Hole Spring’s abundance of sea life makes it a popular destination for scientists, scuba divers and surface fishermen.

Mud Hole Location

Latitude 2615’48″N longitude 8201’06″W

The submarine hot spring vent is approximately 18.5 KM south of Sanibel Island Light House.

What causes spring water temperature?

Florida Spring temperatures depend on a few factors:

  1. Latitude
  2. Ground Temperature
  3. Depth underground
  4. Geothermal hydrogeology
  5. Recent rain conditions

Latitude

Spring water temperature is a few degrees warmer in south Florida, and a few degrees cooler in north Florida.

The sun’s power is greatest at the equator. Land close to the equator absorbs more of the sun’s heat and energy, which makes the ground warmer. Spring water is stored underground, so it takes on the temperature of the ground.

The temperature of most Florida Springs is between 66 F and 97 F. That’s a big range, but most are on the cooler side. North Florida spring temperatures stay around 70 degrees. Central Florida spring water is about 75 degrees.

Temperature and Depth

If a spring system is deep enough it can be warmed by heat from the Earth’s inner core, creating a geothermal hot spring.

Spring-water temperatures range from 66 to 97 °F. The temperature of spring water in north Florida averages about 70 °F and about 75 °F in central Florida. Higher water temperatures in some Florida springs indicate that the water originates from deeper parts of the Floridan aquifer system. For example, the temperature of water discharging from Mud Hole Spring, a submarine spring located off the southwest coast of Florida, is about 97 °F.

Source: “Underground Florida: A Fieldtrip Guidebook of the West Central Florida karst” published by the University of South Florida Scholar Commons

Sources:

American Association of Petroleum Geologists 

American Water Resources Association 

Master’s Research Thesis: Geomorphology of Submarine Spring West of Fort Myers, Florida Shihadah M. Saleem, University of South Florida

Nature.Org: Florida Springs

USGS Mud Hole

Gulf Coast Association of Geological Societies

Mud Hole Spring Wikipedia

USF Water Atlas

“Springs of Florida” publication by the University of Florida

U.S. O.S.T.I. List of Hot Springs in the United States

Geothermal Springs in Florida’s Coastal Waters