We study the localization of Rayleigh waves propagating in a semi-infinite and isotropic medium with inhomogeneities that are modeled as rods parallel to the incoming wave front and are distributed randomly up to a maximum depth. For a perfectly smooth surface, the localization length of a Rayleigh wave is predicted to reach a minimum at intermediate wavelength \ensuremath{\lambda} and to diverge for both low and large values of \ensuremath{\lambda}. For large \ensuremath{\lambda}, the divergence results from the fact that the strength of each scatterer is proportional to ${\ensuremath{\omega}}^{2},$ where \ensuremath{\omega} is the angular frequency of the incident Rayleigh wave. For small \ensuremath{\lambda}, the divergence results from Rayleigh waves propagating closer to the surface and therefore being sensitive to a decreasing number of impurities.