We took Mercury to Alaska last year and when we were pulling away from the dock in San Francisco we happened to be in the back enclosed pool area and the vibrations were unbelievable. The sliding doors were banging so hard in their frames we thought they were going to come out. However, that was the only time we felt this. We were on deck most times leaving the ports and did not feel any other vibrations. Now we had a deck 8 midships cabin and never felt anything coming or going. I can't speak for anyone with an aft cabin. If you are away from the back, you should be ok.