You can rent canoes from Vortex. $10 for 2 hours or $50 for the day.
I have dove Becton Springs a handfull of times, its relatively clear at the moment(or atleast last weekend - waters are lower now, I'd expect better visibility this weekend than last weekend). It is infact, downriver from Cypress. Depths at Becton goto 30 in the main fissure. There is nothing big enough to squeeze into for an overhead environment. A few trees lay across the basin bringing in fish. A large bass has been in the spring the last two times I was there and its seems very curious of divers and has approached within inches of me on the last two occasions. I think I will name this Bass, Bassy.
Twin Caves, Shangri La, Indian Washtub, Gator Hole, Hole in the Wall, and Jackson Blue Hole are all located in Merrits Mill Pond near Marriana, FL. Jackson Blue Hole is the only one thats accessible by land, but to do that, you have to goto the Sheriff's Office and prove you're Cave certified(depending on who's at the Sheriff's office, you have to show either Intro or Full cave certification).
I've dove the caverns of both Jackson Blue and Shangrila, they have rocky bottoms and don't kick up much. Shangrila's cavern max's out at like 13' of depth before turning cave. Jackson Blue's cavern has quite a reach before turning cave. I wouldn't recommend doing either unless you are comfortable diving in an overhead environment - a cavern course wouldn't hurt. Don't dive past your limits.
We tried and failed to locate Indian Washtub.
I dove the outside of Hole in the Wall and Twin Cave but didnt' do any penetration. I was told these caves were very dangerous and silted out easily. A couple of the people in the group I was with silted out the entrances to both quickly. I wouldn't recommend doing anything but looking at them from above.
I'm not sure we were in the 'right' to dive anything in the Mill Pond since we didn't check in with the Sherrif's Office - I'm not cave certified. However, it is a navigatable waterway, so... I dove it.
I have not dove the Bozell Springs or Gadsden Spring. Definately on my list though.