Over the years, the optical system of the submarine periscope has become increasingly more complex. Earliest systems consisted of two simple telescopes arranged such that one could view the output of the other. The visual mode was the only mode, thus the degree of precision called for in the alignment and collimation of the optical components was not great. Today's systems may contain from two to four choices of magnification and, in addition to the basic visual mode of operation, the system may contain a varied array of subsystems including; photographic, television, night viewing and laser rangefinder. Obviously, the procedures and degree of precision to be encountered have become proportionately more sophisticated. This paper will present a brief review of this history and a detailed discussion of contemporary systems and the alignment procedures being employed to assure their satisfactory performance.