WW1 US NAVY H-CLASS SUBMARINES (4) AT DRY DOCK MARE ISLAND CA. WW1 US NAVY FOUR H-CLASS SUBMARINES BEING BUILT BY UNION IRON WORKS AT THE DRY DOCK AT MARE ISLAND NEAR SAN FRANCISCO CALIFORNIA 1918. VERY SHARP FOCUS WITH VERY GOOD CONTRAST. THIS IS NOT A REPRODUCTION OR A COPY.