Ultrafast laser pulses from a Ti:sapphire laser centered at 800nm, with 26fs pulse duration, were used to generate coherent soft-x-ray harmonics, at wavelengths down to 2.7nm (460eV) in He, and 5.2nm (239eV) in Ne. In He, discrete harmonic peaks are observed up to order221, and unresolved harmonic emission is observed up to order297. These wavelengths are well within the {open_quotes}water window{close_quotes} region of x-ray transmission. Our work represents the shortest wavelength coherent light generated to date. The harmonic cutoff from all the noble gases is consistent with analytic theory. {copyright} {ital 1997} {ital The American Physical Society}