I spent several months in Mo. recently. Seems to be a bit restrictive regarding diving despite many beautiful Ozark Springs. There is a Spring and dive shop in Waynesville but it didnt look like much.
I had some nice snorkle floats on the Current and Courtenois Rivers in hot Summer months from a kayak. Amazingly clear water. I saw no reason you couldnt drift dive those although it would be quite shallow. A mix of diving deeper calm pools and snorkling with kayak might be very cool. Outfitters drop you off with bus...you float in rented kayak to their take out place so logistics easy.
Snags could be iffy if water running fast. Big turtles, gars, lots of fish, mink, otters, .crawdads....water snakes...I liked it. Beware the copperheads and cottonmouths but they seemed eager to avoid people.
Lakes were not very clear that I saw although Table Rock was reported to be OK.
I passed on BonneTerre mine as it was quite expensive for my son and I to do for a weekend. Did not have our Scuba gear with either so stayed with the rivers.