In the coming age of multimessenger astrophysics, high energy neutrinos represent unique probes into the physics of the most violent processes in the universe. However, detection of these high energy neutrinos is particularly difficult: at the highest energies (E > 10^16 eV), statistically significant detection is not feasible with current generation, ground-based experiments. Observations of extensive air showers induced by neutrinos from high altitudes may, in principle, solve this problem. By using the Earth and its atmosphere as the primary neutrino interaction volume, large increases over existing experiments can be achieved.
In this talk, we detail the method of Earth-skimming neutrino detection, focusing primarily on detection via the optical Cherenkov emission channel. We highlight the various properties of the expected emission from neutrino-induced extensive air showers, and the challenges and uncertainties involved in this calculation. We also discuss the planned experiments that aim to observe this emission from mountain-top, balloon, and satellite altitudes, their observation strategies, and their expected sensitivities to the diffuse and astrophysical neutrino flux, demonstrating a significant complimentary nature between the optical Cherenkov and the radio detection channels.