To model the dynamic response of a particles-mixture composite, the plane-wave propagation in an elastic matrix containing the structural chiral microstructures had been asymptotically investigated. In this so-called effective chiral (isotropic, noncentrosymmetric) composite, six independent wave numbers can be found from the dispersion equations. Two of the wave numbers represent the nondispersive longitudinal waves while the remaining four represent the dispersive circularly polarized shear waves. According to the dispersion equations, two cutoff frequencies divide the frequency response of the transverse wave numbers into three different groups and the four transverse modes can only be distinguished in a specified frequency range. In this study, the reflected and transmitted characteristics at a water--chiral interface are solved. To further illustrate the effects of the chirality, the reflected and transmitted fields at the water--isotropic and the water--micropolar interfaces are also solved. It is observed that, due to the mode conversion of the chirality and scattering resonances in the chiral medium, the chiral material should instigate a reducible reflected plane wave, and may be used as an anechoic coating to ``absorb'' sound underwater.