Flying Submarines...

[v2]

Flying submarines from Russia

http://www.airforce.ru/aircraft/miscellaneous/flying_submarine/
( who can translate it? )

and from USA

http://www.waterufo.net/flyingsubs/NavyFlyingSubHtml1.htm

what do you think about this "subplanes"?

 

[R988]

I doubt they would work well, too much compromise usually leads to a product that is poor at both tasks.