  We carry out numerical simulations of the gravitational collapse of a perfect
fluid with the ultrarelativistic equation of state $P=\kappa\rho$, in spherical
symmetry in $2+1$ spacetime dimensions with $\Lambda<0$. At the threshold of
prompt collapse, we find type II critical phenomena (apparent horizon mass and
maximum curvature scale as powers of distance from the threshold) for
$\kappa\gtrsim 0.43$, and type I critical phenomena (lifetime scales as
logarithm of distance from the threshold) for $\kappa\lesssim 0.42$. The type I
critical solution is static, while the type II critical solution is not
self-similar (as in higher dimensions) but contracting quasi-statically.
