Simka Choi's come a long way in her career - she's a Cosmos Corps agent in the PRANCER division, responsible for traveling to dangerous places and renovating them to support life again. Maybe they're toxic, maybe they're glitchy, maybe the fabric of space itself is torn open. Whatever the case, she's trained to fix it (or direct a team towards fixing it if it's too big to handle alone).
Her current ongoing assignment is mostly under the ocean, though, and she needed a way to get around. The solution: give her a submarine! And an extra pair of arms, which she used the excuse of needing to steer better to get comped. She's been this way for a year or so now, and the submarine is basically hers to do what she wants with, but until her job is done, she's stuck exploring an ocean full of acid-spewing crystal formations and poisonous coral, trying to clean it up and searching for the cause of it all.