Inside During Rough Seas

This is a crew cabin on a cargo ship. It's bigger and nicer than one would imagine. But then the sea intervenes. You don't see the ship rocking, because the camera is fixed to the wall, but what you see looks like a poltergeist is coming through. How often does this happen? I might be tempted to get some duct tape and bungee cords. (via Boing Boing)