In 1997, in a remote point in the south Pacific Ocean, just west of the southern tip of South America an incredibly powerful ultra-low-frequency noise is picked up by hydrophones monitored by the NOAA. We think sideways in hopes that it will help us to discover the source of this unexplained sound. Learn more about your ad-choices at https://www.iheartpodcastnetwork.com See omnystudio.com/listener for privacy information.