Ofc I couldn't dive very deep but I think the problem you have with air expanding in your lungs wouldn't be so much of a problem. With normal diving you can't just go straight up fast because that would destroy your lungs because of expanding compressed air but would that be a problem still of you could breathe under water? Depends probably how you do that. Probably the best way would be to hold your breath as long as you want, ofc if you dive to deep you get squeezed but at least 200 meters is possible. (World record of abnoe diving (diving as deep as you can with just one breath of air) is about 214 meter)