The Whistle is an unidentified sound recorded by the autonomous hydrophone deployed at a location in the Pacific Ocean with coordinates 80°N 110°W. It was recorded on July 7, 1997. Origin of the signal is unknown, and it was not detected on any other hydrophone. The band of energy between 1 and 6 Hz represents strumming of the mooring in mid-water currents.[1]
Some of the other significant unexplained sounds named by NOAA along with Whistle are Bloop, Julia, Slow Down, Train and Upsweep.[2][3][4]