Surcouf

I thought there might already be images of this sub but couldn't find anything when I searched the site. It was quite interesting. Besides the two 8 inch guns, it had 10 torpedo tubes and an on board aircraft that could have been used for scouting. In practice, it seems to have been used for spotting and correcting fire from the 8 inchers. It was believed lost in the Caribbean after colliding with a merchant ship.

Great find @NebrHogger , a couple of other images of 'Surcouf':

It was the biggest submarine in the world until the IJN I-400 series.