  The nolinear hydrodynamic equations of the surface of a liquid drop are shown
to be directly connected to Korteweg de Vries (KdV, MKdV) systems, giving
traveling solutions that are cnoidal waves. They generate multiscale patterns
ranging from small harmonic oscillations (linearized model), to nonlinear
oscillations, up through solitary waves. These non-axis-symmetric localized
shapes are also described by a KdV Hamiltonian system. Recently such ``rotons''
were observed experimentally when the shape oscillations of a droplet became
nonlinear. The results apply to drop-like systems from cluster formation to
stellar models, including hyperdeformed nuclei and fission.
