Most common annoying one for me would have to be deep cuts on feet from coral, sharp rocks, bottles, discarded knives, syringes, angry fish etc

Injury which scares me the most- being knocked out. Thankfully I didnt drown, was a damn long swim to get my gear in 30 knots.
Box jellyfish, hurt like hell and I slept for 40 hours (literally woke up thinking it was the next day... wha, what happened to sunday

).
Face planted boom, looked like a moron at work for a couple of days.
Twisted knee ligament, that knee sucks anyway so didnt give it much rest.
Thats all in 10 years of sailing.