What gear were ye using to dig?I just spent 2 months digging out foundations at 50-60m on air as a bottom gas on scuba. Was i narced, yup. Was it anything more then inconvenience... For me not really. I had no trouble orientating in 0 visibility or measuring, recalculating and marking stuff. Biggest thing I noticed is that after doing some delicate sledgehammering it would take me a few seconds more to get my breathing under control, i'm guessing that's due to gas density.