March 19, 1912: F-2 Submarine #21 ready for launch at Union Iron Works, San Francisco, California.

USS F-2 Submarine #21 seen in 1912.

USS F-2 Submarine #21 seen off San Diego, California in 1912-1914.

USS F-3 Submarine #22 (left), USS F-2 Submarine #21 (center) and USS F-1 Submarine #20 in drydock
#2 at Mare Island Naval Shipyard. USS Alert is seen in the background. Note the open torpedo tube door on
F-1.

Three of the four F Class submarines at Honolulu, Hawaii. USS F-2 Submarine #21 (left), USS F-1 Submarine
#20 (center) and USS F-4 Submarine #23 (right). This photo was taken between July 1914 nd Nov. 1915.