  Despite significant advances in the field of phononic crystals, the
development of acoustic metafluids that replicate the behaviour of liquids in
three dimensions remains elusive. For instance, water - the quintessential
pentamode (PM) material - has a bulk modulus two orders of magnitude higher
than current state-of-the-art PMs. The need for a low shear modulus inherently
conflicts with the desire of high bulk modulus and density. In this letter, we
shed light on the limitations of existing PM geometries and propose an
innovative shape for the links that constitute the network. Inspired by the
kinematics of ropes, these links are constructed from thin fibres and
demonstrate the potential to create PMs with properties akin to those of
liquids. As a prime example, we present the design of the first metamaterial
that fully deserves the name 3D metal water, since its acoustic properties in
the low frequency regime are indistinguishable with water. Additionally, we
highlight a shear band gap in the lattice dispersion diagram, and illustrate
the influence of geometric parameters on the dynamic properties at higher
frequencies. This novel design of metafluids holds promise for applications
requiring anisotropic materials such as acoustic lenses, waveguides, and
cloaks.
