The dynamics of electron tunneling through water layers embedded between two metal plates is studied by electron wave-packet simulations. The tunneling flux is shown to increase by orders of magnitude due to resonances when the thermal motion of the water nuclei is "frozen＇＇ and transient molecular nanocavities dominate the tunneling mechanism. This enhancement is observed even when the energy width of the wave-packet is larger than the resonance width, and the transmission probability does not show resonance peaks as a function of the impact electron energy. The wave-packet simulations are based on a parallel solution of the multidimensional time-dependent Schrodinger equation, in which the N-dimensional Hilbert space is distributed into subspaces associated with an N-dimensional hypercube of processors. The propagated wave function is fully distributed at all times and the computation rate can increase linearly with the number of processors. The significant advantage of the present algorithm over serial algorithms is in the ability to increase the size of the propagated wave-functions without increasing the computation time by adding more processors. (C) 2000 American Institute of Physics. [S0021-9606(00)51506-2].