Developments in High Energy Neutrino Astronomy

Nature produces cosmic ray particles, probably protons, with energies well above $10^{20}$ eV -- how are they produced? Where do they come from? Gamma rays with energies above $10^{13}$ eV are produced in jets of active galaxies -- are these produced by energetic electrons or protons? What is the correct model of Gamma Ray Bursts? These are just some of the fundamental questions in high energy astrophysics to be answered by observations made with large area neutrino telescopes.