Underwater recording of Weddell Seals by the McMurdo Oceanographic Observatory (www.moo-antarctica.net). Of potentially soniferous marine mammals, only Weddell seals occur in the area at this time of year. Verified also by regular visual/video observation. Hydrophone at 21m deep. (Attached photo is example of Weddell seal near the observatory site, but was not taken at the same time as the audio recording).