This lecture discusses the operation of a Neutrino Telescope in the Mediterranean Sea since 2008, which uses a large water Cerenkov detector with 900 PMTs to detect signals from High Energy neutrinos. It explains the process of detecting neutrinos, their oscillation, masses, and hierarchy. The lecture also covers the detector design, expected performance with angular resolution, and effective area for neutrino detection. The conclusion highlights the detector's use in detecting galactic neutrinos and its contributions to understanding neutrino properties.