Water is the quintessential hydrogen-bonded system, exhibiting exotic and anomalous properties with applications varying from biophysics to planetary science to molecular engineering of energy materials. I examine various perturbations to water's structure due to solvation of ions, nanoconfinement, and high pressure/temperature. Using first-principles molecular dynamics simulations, I analyze in detail both structural alterations to water at these conditions as well as more subtle and intrinsically quantum mechanical quantities, including Raman and infrared spectra, ionic conductivity, and molecular polarizabilities. These studies point to a resilience of molecular properties of water over a range of extreme conditions.
