The distance to these buoys seemed to be about 1/3 mile,so I set out. My wife had bought a cheap underwater film camera for our day in the park and I took this with me, pausing from time to time to snap a shot. Along the way I encountered quite a lot of fish and some nice coral formations. Pretty soon I was approaching the first of the buoys indicated by the ranger. However, looking down, I realized that I was swimming just above a shark that was longer than I was tall.
I'm marginally familiar with shark species, and I seemed to recall that this individual was a member of a rather innocuous breed of shark. However, because he was so large and because I was swimming so far from shore and alone (no other swimmers had ventured out so far), I began to feel like not so much more than something to be eaten by a big fish.
Stopping just long enough to take a couple of photos of this shark (a nurse shark, I've been told), I decided to head back to shallower waters closer to the foundation of Fort Jefferson, where I was only too happy to continue my snorkeling adventure. The better part of valor and all that.