Onethreeseven, Unfortunatley someone being able to dive to 1000 feet on a rebreather, or any other apparatus for that matter, does not support your claim of being able to go all the way to the bottom. The AVERAGE depth of the ocean is over 10,000 feet and the real bottom is at about 37,000 feet. There is NO gas mixture that has been used that can take humans to that depth and sustain life. (these depths have been reached by humans in submarines, but that is irrelevant to the issue at hand.) The deepest dives preformed under pressure by humans have been in the 2000 foot range and even these are extrememly rare and dangerous. Despite this they in reality only barely scratch the surface of the ocean. Human beings are land based organisms, and while we will continue to push the envelope of our physiological tolerances it is highly unlikely that humans will ever even reach the average depth of the ocean unprotected by one atomosphere submersible of one kind or another. The claim that there are no physiological limitations limiting the depth that humans can venture underwater is not true. There are countless physiological limitations that affect humans EVERY time we enter the water, no matter what the depth.