until the dorado outcrop outcrop expedition, how it's filtered through earth's crust. >> you have thehat's circulating through the crust so even if you take a little bit of the pag knees magnesium or carbon dioxide, even a 1% anomaly could be huge on a global scale. >> aboard atlantis technicians work around the crop prepping alvin for its dive as scientists fine tune their experiments. >> tomorrow we'll go to marmer marker m. >> this area is filled with clues on global water patterns and how this life exists without sunshine. the newly discovered scientific data is priceless. >> probably on the order of $50,000 a day. >> and ensuring safety is a big priority. >> there is no other alvin so all sorts of problems can crop up but we have a lot of measures in place to make sure that safety's never compromised. >> before my dive i get an extensive safety training right in the belly of the beast. >> these are the redundant atmosphere detectors and we'll monitor. if you are ever in a problem right to the underwater telephone and call the surface and say you need some assistance. >> apparentl