In this paper, we demonstrate experimentally for the first time (to our knowledge) the generation of spectral supercontinuum (SC) of more than two octaves with high intensity in a water jet. The spectrum of the generated SC extends from 350 to 1400 nm, with intensities up to 1011 W/cm2, and its generation efficiency is more than 50%. For the pump intensity 3.0×1012 W/cm2 in the spectral range from 400 to 800 nm, the spectrum is nearly flat (less than 40% deviation), which is useful for many applications.