5. Hydro Armor 
First Appearance: Iron Man #218 Though Tony's suit does function underwater (as seen in The Avengers and IM3), the suit has several limitations when submerged. In the comics, Tony made the deep sea armor for a government mission, to stop enemy foreign forces from opening a toxic gas tank on the wreckage of the Titanic, that would kill half of London's population. The suit was designed to work at underwater depths of up to 3 miles, and all repulsor weapons were adapted for underwater use. The suit contains mini torpedoes, can generate an electrical field around itself (similar to electric eels), and release a chemical into the water that generates a squid-like inky black cloud. The suit has enhanced life support for deep sea conditions and the main armor can be jettisoned if Tony needed to escape. If Marvel Studios ever decides to take the battle underwater (perhaps in a Namor film?) you can bet that Tony would give himself the proper upgrades to survive the ocean's depths, especially after he barely escaped the mansion attack in IM3 and nearly drowned.