||I first became aware of Uncle Sam through DC Comics, who now own the character. In this story it seems he can breathe and talk underwater, and his hat stays on for the most part. Water pressure doesn't affect his aim when picking up a sub-tank and throwing it. I kept wondering if water went in his mouth when he talked.
By the way, the inside front cover is missing. I saw the fiche version on Comic Book Plus. It has the same ad above the indicia that is on the back cover of Pep Comics #1.