The propagation of sound waves depends on the boundaries between media, speed, frequency, and intensity of sound when transitioning between air and water. At the media boundary, sound waves are partially reflected and partially transmitted, with changes in speed and angle of sound passage. Acoustic attenuation, including absorption and scattering, significantly reduces sound intensity and affects its quality. The multibeam echo sounder is a sophisticated instrument that uses multiple beams of acoustic waves to precisely measure the depth of the seafloor. This technology enables highly efficient and detailed seabed mapping, providing information about the topography and structures on the bottom. Field data collection was carried out using this advanced tool. This study investigates the biocoenosis near the city of Split, with a particular focus on the role and condition of Posidonia oceanica in the area. Analysis results reveal the presence of three main types of seafloor: posidonia, rocks, and sediments. These types were distinguished based on the intensity of the return signal, depth, and terrain slope. Posidonia is a crucial seagrass that forms underwater forests and plays a vital role in Mediterranean marine ecosystems. It provides habitat for many marine species, stabilizes the seafloor, and filters water, while also producing oxygen through photosynthesis. This information allows for a detailed understanding of the distribution and condition of marine habitats, highlighting the importance of posidonia in ecosystem conservation. The discussion of results emphasizes the contribution of the multibeam echo sounder to precise seabed mapping. The study demonstrates how advanced technologies enable more detailed and accurate mapping, which is essential for effective marine resource management and ecosystem preservation. These insights provide a basis for future research and protection of important marine habitats in the Adriatic Sea.