The Pierre Auger Observatory has been used to search for neutrinos of energy exceeding 100 PeV by looking for inclined showers that develop deep in the atmosphere. Neutrinos of any flavor interacting deep in the atmosphere and triggering the Auger surface detector can be identified provided their zenith angles exceed 60 degrees. Also tau neutrinos that enter the Earth’s crust with a zenith angle close to 90 degrees can interact and produce a tau that decays in the atmosphere inducing an “upward-going” shower that triggers the surface detector. The sensitivity obtained summing up these channels is shown to be comparable to other neutrino detectors in operation,
and to constrain several models of cosmic-ray and neutrino production in the EeV region. The declination field of view for neutrino searches in these two channels spans from about -80 degrees to 60 degrees in equatorial coordinates. The Observatory has also been used for searches for neutrinos from point-like sources in the sky. We finally report on the results of the search for neutrino fluxes in coincidence with the gravitational wave events GW150914, GW151226 and GW170104 recently discovered with Advanced LIGO, and on their implications for the total energy emitted in EeV neutrinos by black hole merger events.