Needs for higher resolution, volume of information and longerdata series are becoming increasingly important in oceanographicobservation. In some applications traditional observation systems,such as autonomous oceanographic buoys and measurementstaken from oceanographic ships, present serious disadvantages regardingcosts, volume and delay of data or batteries autonomy. Thenew cabled underwater observatories can be modular, flexible andadapted to different uses and specifications to satisfy the requirementsof the scientific community. The OBSEA project (www.obsea.es) is a collaborative task, between the CSIC (Consejo Superior deInvestigaciones Científicas) and the UPC (Universitat Politècnica deCatalunya), to design and develop a seafloor observatory situatedin front of the “Vilanova i la Geltrú” (Spain) coast into the marinereserve “Colls Miralpeix”. OBSEA is a multiparameter laboratory foroceanographic studies integrated in the coastal zone and a test sitefor marine equipments included in the European Seafloor ObservationNetwork (ESONET).