A handsome, sensitive looking, very young sailor, late 1930s or so, I believe (looking a bit like a young Barack Obama to me!), with his hat reading USS San Francisco.  Commissioned in 1934, the USS San Francisco was one of the most decorated ships of  WW2, used heavily in the South Pacific. I especially like photos of young sailors who look like they've just put on their uniforms for the first time and are posing for a photo to leave with their mother; very tender. 

5 5/8 x 3 7/8 and in good overall condition, with scatterered surface nicks here and there, I don't think detracting.