  We present a comprehensive investigation, combining numerical simulations and
experimental measurements, into the manipulation of water waves and resonance
characteristics within closed cavities utilizing anisotropic metamaterials. We
engineer the anisotropic media with subwavelength-scale layered bathymetry
through the application of coordinate transformation theory and the
homogenization technique to a fully three-dimensional linear water wave
problem. Experimental and numerical analyses of deformed cavities employing
anisotropic metamaterial bathymetry demonstrate regular sloshing mode patterns
and eigenfrequencies akin to those observed in rectangular reference cavities
with flat bathymetry. Our study underscores the potential of water wave
metamaterials in establishing robust anisotropic metabathymetry for the precise
control of sloshing modes.
