The observation of high-energy neutrinos from extreme astrophysical sources would substantially broaden our understanding of high-energy phenomena in the universe, and reveal the origin of cosmic rays. A proposed cubic-kilometer scale high-energy neutrino detector located in the South China Sea, the Neutrino Observatory in the Nanhai (NEON), optimized for the detection of high-energy neutrinos in the subPeV range, is expected to explore more in the multi-messenger era. Here, as a first step toward the optimization and construction of the experiment, the different detector designs, configurations, and geometry of the experiments have been simulated based on the location and environmental conditions. The estimated physics performance is given for astrophysical sources, in particular for the ones with observed high-energy gamma emission.