Aaron -
Blue spring is a fantastic spot for a little freediving in Orlando. I go there fairly often as it's open year round at a constant 72 degrees. It's normally a little cooler at the bottom, no colder than 68 though. Sometimes there are manatees there, but the weather here in the sunshine state has been too warm recently for it being very likely for them to be around.
The spring is pretty shallow on the surface with a large hole in the center like a diagonal split where it drops down. There is a pretty kicking current boiling out of the hole so it's a little different from most constant wieght diving. You are actually swimming (or pulling, which is easier) against the current down and then swimming with the current back up. It drops pretty much straight down to about 70 feet or so before angling back and down (overhead environment) to the opening at the bottom. Once you reach the "floor" at 70 to 75 feet you will need a light to go further because it gets dark, fast. I haven't penetrated all the way down to the cave yet but I can tell you it's a loooooong swim against the current once you pass 80 feet. The spring normally has GREAT visibility due to the water flow. As you are normally sharing the spring with teenage swimmers and perhaps a few scuba divers this is nice because even when they kick up the bottom it normally clears in a few minutes. The water is cool enough that most of the bikini/swimming trunk clad crew rarely stay long.
The spring is home to a few small bottomfeeding fish and the karst topography that formed it makes it really interesting to look at. One of my favorite things to do in this spring is to lay on one of the ledges at 50 feet or so and "watch the world float by". It can be very relaxing and fun to dive there.
Even though the spring is 72 degrees, remember that it is COLD. If you have a 3 mil apnea suit you are set, I normally go in my 5mil scuba suit and hood. A hood is required if you want any modicum of warmth. You won't need gloves. Open cell is not the best option as you normally bump the edges and sides on the way down going hand-over-hand.
This is a great spot for families too. The park has bathrooms to change in, and a small concession stand as well. There is a dedicated swimming spot too. To get to the spring head you follow a wooden path down to the water, then walk up the stream about 50 yards or so to get to the spring head. If you have little ones the walk up to the head can be very educational as there are lots of minnows and river life to be found where it is only 3 to 4 feet deep.
Here are some pics of the site, hope you enjoy em. No housing for the 5060 yet so they are all dry, but should give you an idea of what to expect. I will check my schedule and see if I can get out there this weekend, I would love to meet up with you if I get a chance. There is a good chance on any weekend day to meet other freedivers there as several people on the boards frequent that area.