Geographic Object-Based Image Analysis (GEOBIA) has been successfully employed to map terrestrial environments. However, 71% of Earth's surface is covered by seawater and standard optical methods suitable for mapping the land surface have limited application in such environments. Application of GEOBIA to marine environments has nevertheless been attempted and can generally be subdivided into three domains: 1. The intertidal zone and shallow subtidal zone have been mapped with optical data and application of GEOBIA in such environments can be seen as a seaward extension of terrestrial approaches. 2. Photographs of the seafloor give very detailed but spatially limited information. GEOBIA methods have been applied to classify benthic species and habitats and estimate seafloor complexity among others. 3. Due to the rapid attenuation of light in water, the method of choice to map the seafloor employs sound. Modern multi-beam echosounders map the seafloor in high detail. Such sensors measure the topography (water depth) and the strength of the returning signal (backscatter), which can be used to characterise the seafloor substrates and habitats. This contribution will focus on the application of GEOBIA to marine acoustic datasets. A generic workflow for object-based acoustic seafloor mapping will be showcased and the current state of the application of GEOBIA to marine acoustic data will be discussed.