  The dynamics of an exciton--polariton superfluid resonantly injected into a
semiconductor microcavity are investigated numerically. The results reveal that
a B\'enard--von K\'arm\'an vortex street is generated in the wake behind an
obstacle potential, in addition to the generation of quantized vortex dipoles
and dark solitons. The vortex street is shown to be robust against a disorder
potential in a sample and it can be observed even in time-integrated
measurements.
