Yes, i do get claustrophobic (rarely, but yes). If the effort to go forward is hard, you need to take in account that there won't be space to turn around and sw

Yes, i do get claustrophobic (rarely, but yes). If the effort to go forward is hard, you need to take in account that there won't be space to turn around and swim it head first back. So you need to keep in mind that you might need to "finger walk" yourself back - backwards! That is sometimes an adrenaline accelerator and keeps you from doing stupid stuff. About nitrogen: probably one of the most impotent parts is gas planing: we transport and switch gases suitebale for the depth.. before every dive there is a lot of math.