The Peerless Power of Comics!: Death Waits In The Depths!

Previously, we've seen Tony Stark develop Iron Man armor for missions that called for his armor to include specific features in order to deal with situations than his regular suit of armor was unprepared for--whether it was to rocket into outer space, or to clandestinely approach and infiltrate enemy installations. But since two-thirds of the Earth's mass is covered in water, and since the Sub-Mariner could hardly be counted on to make himself available whenever Stark whistled, it was only a matter of time before Stark would need to outfit Iron Man for the depths of the ocean:

In this case, to recover a canister of death gas that had been developed by an Anglo-American research team prior to World War I. A member of the team had been sent to accompany the canister to America for further testing; unfortunately, that voyage was on the RMS Titanic, and so the canister was sent to the bottom of the ocean floor. The matter is brought to Stark's attention due to advanced photography equipment he'd developed for the exploration of the wreckage--which not only turned up the canister and enabled authorities to trace its origin, but also discovered that the canister was deteriorating.

The Titanic's wreck was discovered two years prior to this issue of Iron Man, which gives the debut of Stark's new undersea armor a comfortable enough margin of years to make its appearance in order to take advantage of the interest surrounding the Titanic's discovery while avoiding eclipsing Robert Ballard's accomplishment. And naturally, Stark had other reasons for having such a suit ready to go:

I even like the golden touch, don't you?

Upon arrival at the wreck, however, Stark is notified by his surface team that a Russian trawler has arrived in the vicinity. And after an earlier encounter in England with Irina Tarasova, a Russian agent who also has knowledge of the canister, Stark realizes that things even at this depth of the ocean may soon be heating up:

In the demonstration of prior such prototypes of his armor, Stark had been forced to make due without some of his regular suit's offensive capabilities--which seemed a sensible way to go with these new suits from an engineering standpoint. Yet with this undersea model, we'd find that Stark has given "Iron Man" a little more latitude in that respect, while adapting his weaponry for the environment.

The drones now dealt with, Iron Man realizes that there will likely be more attacks on the way, which have indeed been set in motion by Tarasova. And since Iron Man earlier in England made his position of strength clear to her in no uncertain terms, she's delighted to return the favor from her control console on the surface:

Being outmatched by the construct, Stark realizes that his escape with the canister is imperative. And thanks to his inventive foresight, he's able to accomplish that while also avoiding pursuit: