All 8 K-class submarines moored together, probably November or December, 1918, in a large nest. There is a host of ships in the background, including a destroyer on the right, and a battleship in the middle. With this many ships the location is most likely the Philadelphia Navy Yard. The K-5 is being painted so its numbers aren't shown. Prior to WW I U.S. subs used a temporary pipe and canvas bridge structure that was taken down each time the boat dived. Once the boats reached the WW I operating areas this was proved to be very impracticable and was replaced by a permanent sheet-metal "chariot bridge" favored by the European submarines in the rough North Atlantic waters. Note that none of the K-class was equipped with a deck gun. They were too small for such an installation, even for the diminutive 3"/23 caliber guns used on the L-class.
