  Neutrino astrophysics offers new perspectives on the Universe investigation:
high energy neutrinos, produced by the most energetic phenomena in our Galaxy
and in the Universe, carry complementary (if not exclusive) information about
the cosmos with respect to photons. While the small interaction cross section
of neutrinos allows them to come from the core of astrophysical objects, it is
also a drawback, as their detection requires a large target mass. This is why
it is convenient put huge cosmic neutrino detectors in natural locations, like
deep underwater or under-ice sites. In order to supply for such extremely
hostile environmental conditions, new frontiers technologies are under
development. The aim of this work is to review the motivations for high energy
neutrino astrophysics, the present status of experimental results and the
technologies used in underwater/ice Cherenkov experiments, with a special focus
on the efforts for the construction of a km3 scale detector in the
Mediterranean Sea.
