It takes a little trust to get into a diving submarine. It takes a lot of trust to get into a diving submarine that you built yourself.
This is Olivier Feuillette, and this is his carbon-fiber submarine kayak contraption. It's human powered, it's not exactly the prettiest design, and it's not what you'd call roomy. Really, it looks like M. Feuillette can hardly move at all inside.
But for all of the claustrophobia and auquaphobia it would give a normal person like me, it gives what looks like the most serene and unbelievable view of the ocean imaginable. You'd have to be crazy to build something like this, but it might just be worth it.