Bioacoustic data from an upward looking echosounder, of the model Acoustic Zooplankton Fish Profiler (AZFP) are published. this instrument was deployed in the MOSAiC Central Observatory. Four AZFP frequencies (38, 125, 200 and 455kHz) are included. This echosounder was deployed on January 29th 2020 and retrieved on August the 3nd 2020, after 187 days of operation. The buoy was placed on a 20-m wide area of level ice surrounded by SYI old ridges of the main floe. Access via the road to the Dark site with a junction to the buoy area right before the crossing of Allis ridge was made. Data from the Iridium messages used to control the surface buoy are also included. These include geographical position together with date and time stamp of the AZFP. An independent GPS tracker of the type XEOS Rover was attached to the AZFP and its GPS track is also part of this data set. For the AZFP data, the initial and final deployment (.DPL) and configuration (.XML) files are included. These describe the instrument configuration and sampling plan. The bioacoustics data sets (.01A,.01B, ..., .02A,...) are consecutive, divided hourly. the first two digits describe the phase of the sampling program being used when the file was created while the letter B and C are for files generated within a same hour when the process is interrupted, for example, when backing up the data from the echosounder. During MOSAiC two AZFPs were deployed. The other one had an AZFP pointing downwards, see doi:10.1594/PANGAEA.949811.