  We present a broadband waveguide for water waves obtained through mere
manipulation of seabed properties and without any need for sidewalls.
Specifically, we show that a viscoelastic seabed results in a modified
effective gravity term in the governing equations of water waves, which
provides a generic broadband mechanism to control oceanic wave energy and
enables confining surface waves inside a long narrow path without sidewalls.
Our findings have promising applications in guiding and steering waves for
oceanic wave energy farms or protecting shorelines.
