The IceCube Neutrino Observatory has discovered a diffuse flux of astrophysical neutrinos spanning several TeV to several PeV in energy. While this diffuse signal is increasingly better characterised, only two individual astrophysical sources of high energy neutrinos have been discovered. They show rather distinctive astrophysical properties and both contribute to the diffuse flux at the percent level. Disclosing the origin of the diffuse emission of high energy neutrinos and its connection to cosmic rays remains of uppermost interest. The seminar focuses on Neutrino Astroparticle Physics and the connections between neutrino, cosmic rays and electromagnetic signals. Challenges and milestone discoveries will be discussed and future opportunities illustrated.