The TRITON's route followed closely the same route as Magellan, whose ship, Victoria, you see on the right (the surviving ship, that is). And the gentleman in the upper left hand corner is not Poseidon (Neptune), but his son... Triton.
Also, the banner could/should read USS TRITON (SSRN/SSN 586), but the submarine was an SSRN at the time of the circumnavigation in 1960; it was reclassified in 1961.
U.S. Navy photograph, obtained here.
To learn more about the TRITON, visit here and here.
To order the calendar, which also features a selection of cartoons about submarine life, and to find out more about DSF, which provides scholarships to children of submariners, visit dolphinscholarship.org