NESTOR:an Underwater Neutrino Observatory in the Ionian Sea

Deep underwater high energy neutrino detection is a very promising field in both elementary particle physics and astrophysics. On one side, the energy range of ground based accelerators cannot be extended much more respect to the present, leaving only astronomical sources for future investigations. In the astrophysics field, neutrinos are the tool to explore further in the universe due to their low interactions. By the same token, the experimental problems for a neutrino detector are enormous. The Cerenkov effect is practically the only possible tool, because it uses sea water both as shield and as detector. NESTOR is the first step toward a full fledged deep underwater neutrino experiment. While its area, of the order of 100000 m^**2, cannot hope to identify all possible celestial sources, it is nevertheless a necessary step toward the "Km^**3" experiment. The first deployment tests have already been performed, proving the feasibility of the mechanical design, and the electronics is almost completely ready. Additional tests are scheduled fir this autumn and next year will see a relevant part of the experiment installed at the bottom of the Ionian see.