In 1998, I spent a week on the Queen Mary. It's docked in Long Beach and serves a hotel.
I saw something twice. I don't know what it was, but it moves through into and out of rooms without opening the doors. Roughly human sized and sort of light gray with a vague shape like it was made of fog. The first time I saw it, I caught just a short glimpse as it passed from the hallway into a room (through the wall or a closed door - too far away to see which). I stared at the same spot waiting for it to reappear until my eyes felt dry.
A couple of days later, I saw it again. It was in a hallway that was cordoned off with "do not enter" signs. I hopped the barrier and walked toward it. Half the brain shouting STOP and the other half shouting HURRY UP! It went into a room and this time, I was close enough to see it went through the door without opening it. I gathered courage and knocked on the door. No one answered. Probably a good thing. I'm pretty sure I would have requried a change of undergarments if anyone came to the door.
I have no idea what it was. I've never seen anything like it before or since. And yes, I was sober.
angela