I like the unusual, this is a model of an acual working submarine. A lifesize model is on display in a park iin Russia. See picture 11.
Russian Submarine. Display model.
Note: The small barrel and extension tube; barrel floats and air pumped down extension tube.
Note: Lead weights (6) on spirals. Turned from inside would allow weights to fall to permit emergency surfacing.
The spike is representative. The actual armament was a flamethrower ignited from inside the submarine.