We were impressed with the German Geologist who spoke for just a few moments. However, what he said put things in perspective..... He stated that the Blue Hole was once a dry cave over 10,000 years ago when Chicago was still under ice... Seems to be the effects of the ice age are still being felt. After further research the melting ice is resulting in higher levels of oxygen in the air and therefore the planet will return to the thick humid air it once was...... Of course that is to happen 10s of thousands of years forward..... More than likely there will not be humans as we know them today.... Definitely some thought provoking information.