Some water snakes have sort of a triangular shaped head and are very aggressive, they can be scary until you know what you are dealing with. We once lived on a river in Maryland and there was a hollow dead tree on the shoreline. We had moved there in December when everything was frozen. The following spring all these snakes, dozens of them, swam up and went into the tree. We assumed the tree was a breeding spot. We were able to determine that they were non venomous but they did chase the kids if they were swimming. You would hear someone yell "SNAKE" and all the kids would jump up on the dock. One struck at my husband once so the following winter when everything was frozen again we took the tree down. For the remaining years we lived in that house some snakes (not as many) would show up each spring looking for the tree.
