sandals and flip-flops are the only authorized foot wear in the Keys.
https://www.google.com/search?q=sandals+fla+keys&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&channel=fflb#q=sandals++shoes+fla+keys&rls=org.mozilla:en-US:official&tbm=shop
I need to come down there and verify that!