"This is from that Groups Photo Album":
Notice the diver? The Fed Alters mention sea attacks too.
The Fountain of Youth National Archeological Park isn't that far from the ocean. May even have a water way in that isn't on the Yahoo Map:
The spring there has a building over it - a planetarium a rock's throw away - statues, etc., and you walk only a very short distance down to the water!
There is a large statue of Ponce de Leon there, and just beyond, supposedly the site where his ships anchored.
It would be VERY easy to approach by any means - boat or plane or a casual tourist on foot making the walking tour.
The crowds were not large, *but" it is located within the city limits! and if a large area were affected - well - - panic and chaos most definitely would be achieved.
Troubling thoughts flow....St. Augustine is a very compact area, full of historic buildings and shops and restaurants and foot traffic.