When a beaver unexpectedly emerged from the far side of the river at sunset & darted towards me, undersea, it was in fact quite frightening. Those things can be thick if they feel that their environment is being threatened. They frequently bring rabies & those front teeth are not to be tinkered.
A very first effort to frighten it by slapping the water with my fishing pole didn’t work. The good news is my stumbling over rocks, almost falling & triggering substantial splashes did. Needless to state, the fish weren’t eager after that!