Is it possible to swim in full heavy armor in this game?
Realism be damned, it would suck to not be able to.
Seriously, you wouldn't have fun if you had to jump into a menu to unequip armor every time you wanted to cross a river without looking for a bridge.
And as far as boundaries go, there were tons of invisible walls in New Vegas, they were at the tops of a ton of mountains that I would have been able to walk up otherwise.