Passenger vessels are predominantly cruise ships, with most passengers beginning and ending their trips in the United States. Cruise ship inspection, involving a large volume of U.S. citizen passengers and crewmembers who may have made several entries in just a few weeks, is handled either upon arrival or en route, using a relatively small inspection staff.En route inspections.Because of the large volume of passengers and crew on many cruise vessels and the rapid turnaround time required for off loading passengers from one cruise and loading for the next, cruise lines may request that CBP conduct the immigration inspection while the ship is en route from the last foreign port back to the United States.Passenger Inspection.Except where an en route inspection has been arranged, passengers will be inspected after docking. Some port facilities have a passenger terminal, with inspection booths provided similar to those at airports.In either case, there are often a large number of passengers requiring inspection in a relatively short time span.