Seaman Zackary Ackerman, a Coast Guardsman aboard the USCGC Sequoia (WLB-215) and Matthew Fowler, a National Oceanic and Atmospheric Administration research technician, disconnect a hydrophone from the recovery assembly in order to retrieve the data recorder in Challenger Deep near the Federated States of Micronesia, Nov. 3, 2015. The crew of the Sequoia and NOAA scientists deployed the hydrophone in an attempt to listen to ambient sound in the deepest part of the Challenger Deep. (U.S. Coast Guard photo by Petty Officer 3rd Class Dylan Hall/Released)