I've seen some really tiny ones on the South side of the island while diving. I usually don't dive with a wetsuit so I tend to feel them right away.
I wish I knew about the urine last August. Whatever stung me in the water surely did hurt. I didn't see anything, but felt it. Ended up going to the clinic because I also had some swelling. Hopefully, it will never happen again, but if it does I know what to do now.