Home made submarine....

I've kinda been obsessed with flying the past few days. But then I did a bit of reading on fluid dynamics (I'm a geek, I do stuff like that) which reminded me: The physics of moving through air and water are very, very, similar - why do you think penguins adapted to swimming so easily?

Why do they swim so well? I'm not jacking you, it's exactly the same physics as flying. Don't believe me? Go look up what a 'hydroplane' is. Who's the physicist? Yeah......

So the next logical step from home-made flying machines would be......