There are a number of stairwells running from top to bottom and when you arrive in your stateroom there is a plan on the back of the door showing you the routes in the event of an emergency. However prior to leaving port on the first night there will be a muster drill and you will be guided to a central point relevant to your stateroom location and then taken to the nearest lifeboats. This is a requirement under international. During the night safety officers patrol the ship. So don't worry and enjoy your cruise.