When I was little, I enjoyed “inventing” things, or drawing designs for things, mostly consisting of aircraft or space ships. One of them was a sub that was constructed out of transparent inflatable plastic, similar to a Zorb ball, so you’d have an unobstructed view of the ocean. It was tear drop shaped and the appeal of the Zorb ball construction was that it’d be comfortable to lie in as you roamed the depths of the ocean. As I got older I learned more about physics and realised what a terrible idea that would actually be.