I've had water snakes come up to me all the time while fishing. We don't have any poisonous water snakes around here that I know of. People I fished with went into a panic before if one came into a 3 foot radius of them. I've had them come up and take a whiff of me and simply turn away. Perhaps that stinky Maumee River water got to them...Hahahaha. I had one who was trying to get a little too friendly and rubbed against my leg. I simply nudged him away. No harm done. It was kinda neat because he was my "fishing buddy" for the day and followed me around. I never had an issue with them. I owned several snakes and despite their awful reputation, they do make nice pets if you treat them well.
However, other animals have not been as nice. I was wading chest deep before and had a ticked off snapper come after me. That definitely got me moving really fast. I've been chased off by a beaver as well. I've gotten chased/attacked by geese too. I have more problems being outside in general with bees and wasps though. I'm allergic to them and they ALWAYS come to me. Doesn't matter how calm I am or anything.