Absolutely it's the pressure, Andy. I haven't been arguing against that. It just doesn't have to be water pressure is all, since you can get the bends from a plane decompressing too rapidly. I think, in the case of water, depth is only relevant in that the pressure increases as one descends, which presumably would cause more nitrogen to dissolve in one's blood, thus increasing the amount present to form bubbles and also making for a bigger pressure change upon rapid ascent, which would cause that larger amount of dissolved nitrogen to form said bubbles.