No just the one hand. You swim faster with nothing equipped as well.
Yes, brain coral is good as I said for extending your dives before you build a submersible. Like an air ladder..
You want to start a base soon as you can line the walls with lockers. Mine filled an entire multipurpose room, every space had a locker on it, all for different mats and labeled. Usually several for titanium. And each of my four bases had locker storage of course. I built a second seamoth with three storage racks just to use to transfer stuff to new bases under construction.
Animals flee this hell, the hardest stones cannot bear it for long. Only men endure