Bringing the dog? These springs allow leashed pets in the park. Note that dogs are almost never permitted in the spring water itself, even where they are welcome on the grounds.
8 springs

Wes Skiles Peacock Springs State Park
One of the longest underwater cave systems in the country.
Lithia Springs
The closest real spring to Tampa.
Hart Springs
A well-run county park on the Suwannee with real facilities.
Otter Springs
A quiet RV-and-camping base near the Suwannee.
Suwannee Springs
Historic sulphur springs and 19th-century ruins on the Suwannee.
Vortex Spring
The Panhandle's dive resort — training, cavern, and camping.
Cypress Springs
The clearest water in the Panhandle — reachable only by paddle.
Chassahowitzka Springs
The wildest spring-fed paddle on the Gulf Coast.
Policies change and vary by area of each park — always confirm with the park before arriving, and never leave a dog in a hot car while you swim.