Hmm. I could see that. A cruise ship or something overrun, like a ghost ship, found adrift by scavengers, who get lured in search of riches. The rats eat the scavengers for food. That's how the rats survive on the cruise ship, (that and cannibalism, eating all the sicker, smaller, and weaker rats). And thus, the ghost ship continues to drift, never really found, but never really lost.