Plenty of nice places to plunk in the water - most of them are off the docks. Most places that sell refreshments that have a dock will let you plunk in even if you are not staying there, as long as you are a customer. The people at Amigos Del Mar Dive Shop always welcomed us to their swim area as well.
Don't worry San Pedro Sharks don't bite!

broke my leg skydiving the first time so I had to do it again so I wouldn't be afraid to do it some more! It is awesome! You do have much more personal control in the water snorkeling with the pretty little fishies!
Belize it!