The paper presents the results of the first program of large scale side-scan sonar surveys for environmental purposes on the Romanian waters. The methodology used for the scanning, data processing, analyses of grab samples and the mapping of the main types of sediments for drawing of habitat extents are described. Data processing ended with the segmentation of the sea floor based mainly on backscatter data pattern from which the acoustic classification of the sea floor was derived. A total number of five sites were analyzed, covering a total area of 13635 hectares. Five main acoustic facies were identified, out of which three are present within the “Underwater Sulfurous Seeps from Mangalia” Natura 2000 site, the NATURA 2000 site used for exemplification due to the variety of sea floor types.