Breaches happen fairly infrequently, and you're effectively swept into the reality of some other universe and think you've lived an entirely different life from the one you're used to. A similar occurrence can happen during ports, but breaches affect everyone, and the Barge itself. Floods are more regular, and they have extremely varied effects. Not everyone is affected, and there's no way to determine who will be or what changes the flood will create before hand. Sometimes you'll find yourself bursting into song for no apparent reason, or everyone will be animals, or think you've lived a completely different life because you never met someone important to you, or you'll swap places with someone from back home. They usually only last a few days.

... I switched placed with you, for a few days last year. I don't remember much of the details, but there will probably be some people who'll recognize you from that.