Madison Blue Springs State Park

A nice park, easy to find. $ 5/​car entrance fee. Has a restroom, with changing stalls. No showers. Has picnic tables!
The water is about 65 – 70 degrees year round! They have newer entrance to the springs, nicely maintained. The stairs into the water are a little slippery, but ok if you are careful.
I would recommend bringing a mask to check out all the cool stuff underwater! At the very least wear some WATER SHOES or sandals that strap on, the rocks on the bottom are covered in moss and can be super slippery and some of the rocks are sharp!
We came on a very warm November day (80 degrees!) and after 4pm, we had the whole place to ourselves!
Only negative I can say is, avoid going when there is a dive group. (But that is not the fault of the park.)
There was a group doing a cave dive when we first arrived. They were a little disrespectful of «sharing» the space. And acted as though they had priority over the space. They took up both sets of stairs into the water and had their equipment all over the place. We had one small backpack on the bench with all of our dry things… towels, clothes, etc. When they got out of the water, we noticed they put their wet equipment next to it. We moved our things to be polite and kind of get out of their way. However, when we got out of the water, they had moved their things onto the bench with our stuff and had soaked our dry stuff. They also kept spitting all over the place, which was super gross, as I was in my bare feet. We were swimming, after all!

A fairly small State Park but one dedicated to a beautiful, pristine spring that feeds into the Withlacoochee River. The spring is popular both with swimmers and SCUBA divers doing cave diving. The park facilities are fairly basic, with a ranger station, parking lot, bathrooms, and pic-​nic tables plus the spring itself. There are some hiking trails also but I don’t think overnight camping is allowed. At one time, there was a diving dock to dive into the spring but sadly it was removed, supposedly because a kid broke his arm when pushed off of it by his brother, but who knows.
A word of warning, though: the spring is 25ft deep and first magnitude with a very powerful outflow and there are a line of sharp rocks across the spring-​run to the Withlacoochee River. These are very slippery and the outflow is so strong you cannot swim back against it. My friend and I both slipped and fell here, getting pretty cut up in the process. I rock climb – I was just in North Carolina and did some free-​soloing there so suffice to say I’m pretty sure and steady of balance but down I went. Be very careful if you’re swimming here when you reach these rocks and moreso if you stand up. A small child could be swept right over them, even. This is a beautiful and fun spring to visit, make no mistake, but the rock situation was one I’d not previously encountered at a Florida spring.