Armin was tired, and hungry, and injured. But most of all, he was so filthy he was practically unrecognizable. Before he could tend to his other needs, he had to get clean.

First, after taking off his boots and detaching all his gear, he plunged into the ocean, uniform and all. There was so much mud caked on him that he wouldn't be able to get out of his clothes until it was washed off... He was too attached to his uniform to just cut himself out and throw it away.

Once he could free himself, he stripped down to his underclothes and spent a long time scrubbing his cloak and jacket as well as he could. The warm, salty water did a good job of cleaning the muck out of his uniform, and stung at his contusions in a satisfying sort of way.

With a couple of good pieces of driftwood, he set up a rack for his uniform, and then set his attention to maintaining his maneuver gear. If it rusted or got dirt in the wrong places, it could become inoperable. He cleaned out his sheathe-boxes, polished his blades, disassembled his engine, tested his triggers, oiled the straps of his harness, and laid all the intricate pieces in perfect order on the sand to dry out and cure.

Then he waded into the ocean for a second time to try and clean himself. It takes a damn long time to get all traces of dirt out of blonde hair like his.