Guash, J., Mánuel, A., André, M. OBSEA: An Expandable Submarine Observatory Proceedings of the Sea Tech Week, Brest, France, Oct 2006 Résumé: Submarine observatories represent an exceptional technological resource that supposes a qualitative jump in the investigation of marine sciences. These observatories can acquire and analyse long series of high resolution data ranging from annual tendencies to singular events. The capacity to include spatio-temporal scales of observation provides new opportunities of investigation and development, in basic investigation as well as in technological innovation. This project includes the design of the first Modular Submarine Observatory in Spain (Vilanova i la Geltrú, Barcelona), that would allow: a) Accessibility (shallow waters). b) Modularity (incorporation of new sensors). c) Multi-disciplinarity (integration of data: geological, geophysical, chemical, biological, acoustical, etc. and its later analysis). d) Cost-Effective (as opposed to methodologies that requires different platforms). e) Long-term acquisition (continuous acquisition of series of data). Projet: Noise pollution effects on cetaceans