I've done geocaches where almost every log mentioned bird (more specifically, goose) poop but the there was nothing on the cache page about it.
I swear, the best geoaching stories posted in the forums are often from "former" non-geocachers that stumbled upon a cache and come here to find out what to do with it. I don't think I can recall someone finding one floating in the ocean though but there have been cases of caches found that floated down a river after a flood and one that floated across one of the great lakes.
Great stories. Love it!