  Several projects are concentrating their efforts on opening the high energy
neutrino window on the Universe with km-scale detectors. The detection
principle relies on the observation, using photomultipliers, of the Cherenkov
light emitted by charged leptons induced by neutrino interactions in the
surrounding detector medium. In the Northern hemisphere, while the pioneering
Baikal telescope, has been operating for 10 years, most of the activity now
concentrates in the Mediterranean sea. Recently, the Antares collaboration has
completed the construction of a 12 line array comprising ~ 900
photomultipliers. In this paper we will review the main results achieved with
the detectors currently in operation in the Northern hemisphere, as well as the
R&D efforts towards the construction of a large volume neutrino telescope in
the Mediterranean.
