In northern Florida there are tons and tons of clear water springs that hold a constant water temperature of 72 degrees year round. At Ginny Springs, you can snorkel, or try your hand at cavern diving (where you can always see the surface)...and of course this is also one of the biggest places for people looking for more advance penetration cave dives. I am only recreationally scuba certified, but it was an amazing place to get the feeling of being in a cave and looking up to the sky. I loved this image of the diver swimming overhead creating a stark silhouette