The main objectives of the KM3NeT are the discovery and subsequent observation of high-energy neutrino sources in the Universe and the determination of the mass hierarchy of neutrinos. These objectives are strongly motivated by two recent important discoveries, namely, the high-energy astrophysical neutrino signal reported by IceCube and the sizeable contribution of electron neutrinos to the third neutrino mass eigenstate as reported by Daya Bay, Reno and others. Neutrinos are fundamental particles, probably best known for their reluctance to be detected.
In this colloquium, I will present the rationale as well as the technique of detecting neutrinos from the cosmos.

Passcode: 822762