The U.S. submarine force has always been keenly aware of a particular threat -- men trapped in a submarine that is stranded on the ocean floor. To prepare for that eventuality, the Navy trains personnel for individual escape and for rescue by a chamber from the surface. The operation order that covered search and rescue of submariners was identified Exercise 1000. If an actual disaster struck, it could no longer be termed an exercise and would be designated Event 1000.
