A German sub destroys a rowboat, a buoy, and another German sub. Meanwhile, Popeye, with a boat full of "spinach fer Britain", rams into the sub by accident. The sub cuts Popeye's ship in half with machine-gun fire, separating him from the spinach; it then sends a torpedo into the remains, which Popeye collects in a rowboat. Popeye spins the sub upside down, then ends up in a mine field.