This is TRIGGER (SS-237) in August of 1944, after completion of a lengthy refit period at the Hunter's Point Naval Shipyard in San Francisco, California. She is camouflaged in Measure 9, with Dull Black (BK) on all surfaces.
TRIGGER shows very typical mid-war features for a GATO class boat. The SJa surface search antenna with its mesh grid paraboloid reflector sits atop the small mast ahead of the periscope shears, with the usual SD dipoles on the antenna mast aft. The early TBT (target bearing transmitter) sits just forward of the new 40mm Bofors on the fairwater, and the small stub antennas of the APR-1 radar countermeasures system have appeared on the periscope shears. The radio direction finding loop sits between the SJa mast and the forward periscope.
TRIGGER's armament configuration reflects war experience; a 40mm Bofors single mount (similar to that used by the Army) has been fitted on the fairwater's aft position, with a 20mm Oerlikon forward and a second 20mm gun on the forward gun foundation on the main deck. A 4"/50-caliber Mark 12 wet mount aft of the fairwater completes the armament. The 40mm guns were especially prized for shooting up the small sampans and fishing boats normally used by the Japanese for picket duty.
TRIGGER would be sunk by combined air and surface ship depth charging on 28 March 1945, during her twelfth war patrol.