What I have learned in a brief research on the web today is that you would enter the country in which the ship (or today the aircraft) was registered. The "State" would be the name of the vessel or perhaps the airline. The "Town" would be where the vessel or aircraft was at the time of birth. For example, "On Open Sea", or "Bay of Biscay", etc. The child's nationality depends on the laws of the country to which the vessel is registered and/or the laws of the exact place over which or within which the birth occurred. See this Wikipedia article: http://en.wikipedia.org/wiki/Birth_aboard_aircraft_and_ships