Multibeam snippet raw data were recorded using a Norbit STX WBMS multibeam echosounder mounted to the side of the 6.5 m-long aluminum catamaran KLAASHAHN. Data were recorded using different frequencies in three months in 2019: May (200, 400 kHz), August (200, 400, 550, 700 kHz), and October (200, 400, 550, 700 kHz). Files are stored in the s7k-format, and sorted by date of acquisition and frequency. The 200 and 400 kHz frequency data were manufacturer-calibrated. Correct absorption values have been applied during the export. Data can be processed, e.g., with the open source software package MB-System (Caress, D.W., and D.N. Chayes, MB-System: Mapping the Seafloor, http://www.mbari.org/products/research-software/mb-system/, 2021). The investigation site was located in the Southern Baltic Sea close to the city of Rostock (Germany) and includes three habitat types: seagrass meadows, a mussel covered reef, and coarse sand and gravel areas. Distance to the shoreline was 500 to 1000 m, and water depth varied between 4.5 and 6.5 m. The same area (500 x 500 m) was covered at all times, but profile direction (N-S or E-W) was adapted to weather conditions. Acoustic backscatter strength can be used to identify the seafloor composition. The aim of this study was to investigate the impact of seasonal habitat changes on backscatter strength of different frequencies.