Cypress Springs, located in Northwest Florida, has a rather large spring basin. The outer depths are about 25 feet deep but a small opening can be penetrated to a depth of 75 feet. Several cypress trees are in the spring. There use to be a small dive shop and supply store there. This spring was highly populated when it was accessible by land and was a great checkout dive. Florida State University had it's dive training here for several years. If you go, I suggest bringing everything you need with you including a wetsuit. This spring offers a good half day dive/swim.
Unfortunately in 2002 Cypress Springs and the surrounding land was purchased by Nestle Waters to bottle water. This is now private property and only accessible by canoe or small boat. You must launch at a ramp on Holmes Creek several miles downstream and paddle upstream to reach the spring. Some parts of the river are very shallow. The journey is worth the paddle.
Sadly this is another amazing natural resource that a large corporation has taken over for their own profit. We've seen it happen to several springs throughout Florida and to make things worse they've closed access by land to something that belongs to the people. The great thing is navigable rivers are owned by the public under law so you can still access this gem.
Cypress Springs has incredible visibilty. There used to be canoeing and tubing available.