Forintos Gyula's first submarine, SS86H, was extensively demonstrated to the Hungarian military for river use in the early 1990s, particularly for mine clearance. That proposition is a serious one as the Danube has been mined repeatedly in WWI and WWII and unexploded mines remains a threat. The Hungarian Defense Forces did not purchase the sub.
The later SR93H is a highly stylized design with a military/sci fi theme but underneath is a true sub intended for a scientific polar expedition which sadly has yet to materialise. Despite its relatively great length, the pressure hull is very small diameter and the 5-6 man crew have to crawl and crouch at all time within the hull. Although it may not be the most practical or capable design, its mean looks deserve a film opportunity.
Spurdog
L - 20m
Built in the late 1980s in Holland by two guys who watched Das Boot and were inspired, this boat more recently suffers the indignity of being a houseboat.