These data consist of both underway and station echosounder observations collected during the 2020 SUMMER (Sustainable Management of Mesopelagic Resources) Mediterranean cruise (30 September 2020 to 18 October 2020) on the RV Sarmiento de Gamboa. Narrowband (18, 38, 70, 120, 200 kHz) underway acoustic data were collected continuously using hull-mounted Simrad EK80 echosounders. The recording depths for the 5 frequencies were 1000, 1000, 750, 500, and 200 m respectively. Calibrations were carried out on the 1st of October 2020 using a 33 mm tungsten sphere,and the calibration results were applied to the instruments. During the survey, a Simrad wideband autonomous receiver (WBAT) was deployed down to a depth of 500 m whilst on station. In total, 31 drops were carried out at 5 stations. Four transducers (central frequencies were 45, 120, 200, 333 kHz) were operated using the WBAT in frequency modulated (FM) mode (bandwidth ranging from 45 to 445 kHz). The WBAT calibration data were collected using a 33 mm tungsten sphere. During the deployment of the WBAT, the hull-mounted EK80 was switched to FM mode to record broadband measurements. Raw power (W), number of transducer segments and transceiver impedance (Ohm) were stored in raw proprietary Simrad format (.raw, .idx).