Photo from a B-25 Mitchell running right over a Japanese ship very low during a raid on Hong Kong. Notice bombs in the air on the left, and blurred outline of the plane's twin machine guns in the foreground (presumably this photo is through the tail gunner's window). The separate B-25 that is dropping those bombs is outlined in shadow on the water at the end of the guns.
From a mission on Hong Kong, 491st Bomb Squadron. Click here for a detailed description of this mission.