Yeah, we did wear those helmets - only in school though. Most of the time we used SCUBA gear and sometimes a Jack Brown mask with surface supplied air.
I remember watching documentaries and movies of Greek sponge divers wearing those huge helmets and gear that looked more befitting of an astronaut. I would think, "There has got to be a better way!" I imagine the SCUBA gear has pretty much replaced all of that except for extra-deep diving.
I've only been snorkeling down the Keys and *that* was a blast. I can only imagine how beautiful deep sea diving must be!