I had a Idea. When a surface ship sinks they release a section of the ships deck or structure that floats to retrieve the ship. Opposite the submarine by nature when they sink nothing floats as a floating marker and is real hard to find in different visibility and depths of water, well here go's. Build a submarine that takes hits like usual but with contacts inside the hull that are touched by water or a float switch when trigetrig brings the sub to the surface, has a set of lights go off with different colors, and deactivates the ability to submerge or fire the wepons. There is a second idea I have but I will add it later when the thought is vetoed or outright rejected.