Iron Man 3 introduced a lot of new armours for Tony Stark to use in his battle against Aldrich Killian and A.I.M., and Marvel Studios concept artist Phil Saunders has now shared a closer look at the Mark 37 suit. As you can see, this was meant to take the hero beneath the sea, and looks undeniably badass.
Interestingly, Saunders explains that it started life off as a sketch for 2008's Iron Man after then producer Avi Arad pushed for a Hall of Armor scene "presumably to boost toy sales."
That sounds like the sort of thing the longtime Spider-Man producer would do, and it seems likely Marvel Studios President Kevin Feige overruled him (it's no secret that they don't see eye to eye). Remember, when Arad was fully in charge of the Iron Man franchise, the plan was for Tony Stark to have a transforming toaster or something along those lines.
Check out this Iron Man 3 concept art below: