This is Silver Springs in Ocala. A very popular tourist attraction in central Florida, back in the 1960s.
The spring fed water is crystal clear and cold. One of the main attractions was glass bottom boat trips.
What I remember about Ross Allen, was his exhibit of milking (extracting venom from) rattlesnakes.
They would then donate the venom poison for antidote research.
https://youtu.be/zj5MF_nBmbo
https://www.floridamemory.com/fpc/moz/MOZ00697.jpg