The knowledge of the marine subsoil is a fundamental fact for the correct development of a modern and sustainable dredging project. An accurate defnition of all geological deposits and their dredgeability is directly related to a realistic cost estimation and to the employment of the most efcient equipment. In this sense the combination of geophysical and geotechnical techniques allows optimizing marine investigation surveys and obtaining more precise subsoil models in terms of morphology and dredgeability properties of the diferent units involved. The experience in this kind of projects in diferent sea conditions and a widely range of soil/rock has allowed defning the most appropriate research techniques as well as the suitable equipment and the necessary type of vessel. This paper also presents some brief results of a geophysical and geotechnical marine investigation carried out in the Port of Langosteira (A Coruña, Spain) for dredging works in a rocky seabed.