The deck officers have a white collared job; with the development of technology their jobs have eased up a lot as compared to the days when Columbus set out to sail across the seven seas. Just imagine if you are in the middle of an ocean and only have the stars to guide you, where would you head to? This problem was faced by the earlier sailors and they developed several techniques for finding the position and direction of motion of the ship using stars as relative markers. Later on several instruments such as sextant were used for the same purpose.
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With the development of hi-tech radars, vision aids, Navigational Telex and the GPS system these things have become much more reliable and easy for the navigating officers. The place where the navigating officers perform their duty (or watch) is known as the bridge and is mostly on the top most level of the accommodation of the vessel. This is in contrast to the place where engineers work (Engine Room & Engine Control Room) which is below the main deck level (comparable to underground level on earth) and the only things visible are the machineries. Of course the current trend is to have a combined bridge and engine control room at one place though still the old pattern is mostly followed. See the adjacent picture to get an idea on what a bridge looks like.
