I hate to see you DNF before you even start, BUT... there's no way I'd get in the water with those creatures. I'm with you- if I can see them- they can just have the water. Who knows? Maybe with all the thrashing swimmers they'd keep their distance, but you'll probably be so spread out they may decide to come close and check you out (and sting you in the process). Maybe if every part of my skin was covered I'd do it (gloves, neoprene socks, face mask, etc).
I think if you do it, you're a super brave woman. I don't think I could do it.