Today we entered the decompression phase of our mission, gradually venting the excess nitrogen from our bodies by decreasing the air pressure in the habitat little by little. As this happens, we breathe out the nitrogen at a safe rate and virtually eliminate the chance of a "bends hit" by the buildup of nitrogen bubbles in blood vessels or joints.

Decompression takes about 17 hours, and we are literally locked into the habitat during this time. We couldn't leave even if we wanted to (except in a severe emergency), since the outside water pressure exceeds the air pressure in the habitat by so much that the doors are held shut by many tons of force! We began by breathing pure oxygen for a hour, to begin the rapid voiding of nitrogen gas as we exhaled. This is followed by a much longer phase of waiting in the habitat until we reach a pressure of 1 atmosphere (in other words, normal air pressure) inside. Then, at about 8:30 in the morning, the outer airlock will be closed off and repressurized so that mission support specialists from the surface can enter and escort us back to the world of the sun. We will leave through that same airlock, much as astronauts move between air in their vessel and the vacuum of space. To help us through this complicated procedure, we now have 3 habitat specialists inside with us to carry out the proper sequence of pressure adjustment. They will work through the night, giving the scientists a chance to get some badly needed sleep.

Naturally, we look forward to seeing our friends and families again, while at the same time we are sorry to see our crew end its special time together and disperse to our far-flung home institutions. We have a huge pile of data to analyze, many new perspectives on the plight faced by reefs worldwide, and optimism that increased awareness and knowledge will help us to meet the challenges ahead.

As I type these words, a school of squid hovers outside our lighted window. They're hunting for their prey - tiny zooplankton, mysids, and (horrors) even the occasional baby squid. Their agility and intense desire to survive motivates us, in turn, to do our part to keep their world intact.