This is an original Kriegsmarine greatcoat. It's the heavier guard coat with the attached wool lining and vertical pockets. It appears to be dated 1938. These are quite rare for the Kriegsmarine. It does show use as it has patch marks.
This is a heavy coat, probably 10 pounds. Measurements are approximately 18.5 inch shoulders, 21 inches armpit to armpit, 24 inch sleeves, 46 inches from shoulder to end of coat.