  We address ring-shaped surface waves supported by defocusing thermal media
with circular cross-section. Such waves exist because of the balance between
repulsion from the interface and deflection of light from the bulk medium due
to defocusing nonlocal nonlinearity. The properties of such surface waves are
determined by the geometry of the sample. Nodeless ring surface waves are
stable for all values of their winding number, while surface waves with a small
number of azimuthal nodes can be metastable.
