[laughs] narrator: brief breaks betwtween passing storms allow just enough time to o deoy t the hrophphones to the sea floor. when all systems are e go, the ship releasases the orange floaoats m eir anchors, lifting the underwaterer microphones to ther intendeded depths. zampolli: and thenen... bang--you see these things arrive and then you start finally seeing data. you start hearing whales, you start... you suddenly have eyes underwater. narrator: from the indian ocean down to the arctic sea, from the atlantic to the pacific, hydro-acoustic station number 4 at the crozet islands is now online, relaying data in real time to ctbto h headquarterers n vienna. the data is analyzed and shared with its test ban treaty member ststates almost as fast as it comes in. with 90% of its entire international monitoring system in plalace and its capability to monitor the world's oceans complete, the ctbto can detect and alert the world toto any potential nucleaear test anywhee on the planet, 24-7, 365 a year. [indistinct] [rumbling] [beeping] [doctor speaking english] [leader speaking arabic] [girl cryin