Abstract: The internal subharmonic resonances of the parametrically excited nonlinear waves are further investigated experimentally. It is observed that, other than the well-known Faraday resonance, there exist a series of internal subharmonic parametric resonances at the frequencies fractional to the forcing one such as 1/4, 1/6, 1/8, 1/10 and 1/12, which lead to the excitations of some lower order surface-wave modes. The internal parametric resonances are due to the strong nonlinear coupling among the surface-wave modes. The complex dynamic behaviors, e.g. the mode competition, of wave motion near the boundary of the stability ranges are also observed. There exist some characteristics of chaos in the mode competition. The cascading subharmonic resonances and mode competition may cause chaos.