I purchased this dagger about a year and a half ago at an antique swap meet at the Rynek in Krakow. The seller said it was Danish, but the general appearance looked quite Polish to me. I took a chance though I have no clue what country it's from.
It certainly not Danish, but there are several variations that could rule it out as Polish (including the submarine emblem?). The blade is stamped Solingen on both sides. Any info or guesses would be much appreciated!