K-5 departed Boston, Massachusetts, on 16 November for Newport, Rhode Island, where she joined 4th Division, Atlantic Torpedo Flotilla, for experiments and exercises to develop the techniques of submarine warfare.

She operated for almost three years along the Atlantic coast from New England to the Gulf of Mexico conducting underwater maneuvers, undergoing diving and torpedo firing practice, and training submariners.

As the first U. S. submarine to cruise European waters during the war, they operated out of the Azores searching for enemy U-boats and surface raiders.

After cruising the Mississippi River to St. Louis, Missouri, she sailed from New Orleans 27 July 1919, for operations between Key West, and Havana, Cuba.

For almost two years she ranged the eastern seaboard from Cape Cod to the Florida Keys, participating in numerous experiments and maneuvers to improve the operations and tactical abilities of the submarine.