To stay in an underwater habitat longer than 12 hours means to stay under saturated conditions, which requires an aquanaut decompression sequence of at least several hours. This decompression procedure is very critical: if any aquanaut gets into an emergency situation, there is no way to take him out of the chamber before the sequence is finished. If the procedure is badly designed there is no way to bring a paramedic into the chamber. For the period of several hours the aquanaut would be alone with his companion. Contact us for access to the full article.