Submarine would be easier in a sense. Personally, I feel like I’m falling over in even mild negative Gs, and then you add the health issues. The view would be pretty cool though, and I could have actual bandwidth for communication. (Seawater blocks most things)

I’m going submarine, because I like boats and prefer text communication anyway. If it’s WWIII, a submarine might be the safest place on the planet to be, and among the most comfortable, so it’s a no-brainer.