The Oceanic Armor is an unlockable armor set with that “I’m a deep sea diver” look to it.
To unlock the Oceanic Armor, you’ll have to rank up all the way to SR-47.
The only exception to this is the Oceanic Armor & Circuit Skin that was available through pre-order at Walmart or Gamestation.
You should be able to find a code for the Oceanic CRCT Armor on ebay though if you really want it. As of writing this article, there are a lot of them currently for sale. Below is a pic of the Oceanic Armor & Circuit Skin.
Check out my other guide for the complete list of unlockable armor sets in Halo 4.