Crew size varies, depending upon the type and class of submarines concerned, but a typical U.S. Navy submarine crew consists of 14 Officers, 18 Chief Petty Officers (senior enlisted men), and 109 other enlisted men. A submarine will sometimes go to sea for short periods with fewer crewmen than this because there are crew members on scheduled leave or at shore training facilities.

Typically, the submarine "day" is 18 hours long. Most submarines divide their crews into three watch sections. At sea, each section is on duty for 6 hours, and then spends 12 hours "off watch." When on watch, the crewmen are actively operating their assigned equipment. Under normal conditions, there are approximately 25 crewmen "on watch" at the same time. Under special conditions, such as during battle stations and when entering or leaving port, there are many more.

During the 12 hours of each 18-hour "day" that submarine crewmen are "off watch," they may engage in a great variety of activities. The ships carry about 400 movies that are exchanged for different ones at each port. Card games and various board games, such as a Backgammon or Cribbage, are popular. There are also some athletic facilities on board, such as an exercise bike, versa climber, rowing machines, and free weights.