Cruise ships can cruise in oceans or rivers. Gibraltar Cruise Terminal receives a large number of visits from cruise ships. The ship is also used for cruising, including an annual world cruise. Concorde's maximum cruising altitude was ; subsonic airliners typically cruise below . The port is popular with cruise ship operators. Seward is a destination for cruise ships. It also adapts very well for performance on cruise ships. The main port of call for cruise ships is located in Kahului. The next scheduled cruise was cancelled. It could also cruise supersonically without afterburner, as demonstrated on a delivery flight. Ballistic missile submarines differ in purpose from attack submarines and cruise missile submarines. The crew was unable to see the Moon for much of the outward cruise. Norovirus is a common cause of epidemics of gastroenteritis on cruise ships. Cooper later reports she was sent on an extended "ocean cruise" to heal her psyche. Without the WS-15 engine the J-20 can't cruise at supersonic speeds.