I'm amazed the basic underlying idea (which I believe the designer has been working on for some time) has taken so long to get real traction. In essence, the submarine is an underwater "airplane" that uses the principle of "lift" to go down (so if its engine fails it "falls" to the surface). This means no ballast tanks and a very simple, robust design (mechanical stuff outside the bubble; life support and people inside).<p>Oddly enough the only reason I know anything about this subject is that back in 1997 I was working as a game designer working on a "Tomb Raider"-like game but with the emphasis on the underwater gameplay (I thought Tomb Raider's underwater stuff was a huge missed opportunity, since I found the few underwater bits the most scary and tense).<p>Researching the back story I looked into what was happening in submarine design (a field that doesn't get a huge amount of coverage, even among geeks) and found out about these underwater "planes" and some stuff the US Navy was experimenting with (i.e. a modified Los Angeles class submarine that could launch armed drone subs, which is a brilliant idea since the most dangerous thing an attack sub can do in combat is launch a torpedo).<p>Again -- funny how slow progress seems to be in subs compared to everything else.