"We're just trying to piece things together in a logical way," Isadore said. "River otters sometimes even stow away on boats, we just don't know."
Rare San Francisco river otter stumps researchers →
"They do need freshwater to drink and keep their fur clean," Isadore said. "They are also happy in salt and brackish water _ wherever there is food _ and he is getting freshwater from seeps behind the baths."