  We present a public catalogue of voids in the Baryon Oscillation
Spectroscopic Survey (BOSS) Data Release 11 LOWZ and CMASS galaxy surveys. This
catalogue contains information on the location, sizes, densities, shapes and
bounding surfaces of 8956 independent, disjoint voids, making it the largest
public void catalogue to date. Voids are identified using a version of the
ZOBOV algorithm, the operation of which has been calibrated through tests on
mock galaxy populations in N-body simulations, as well as on a suite of 4096
mock catalogues which fully reproduce the galaxy clustering, survey masks and
selection functions. Based on this, we estimate a false positive detection rate
of 3%. Comparison with mock catalogues limits deviations of the void size
distribution from that predicted in the $\Lambda$CDM model to be less than 6%
for voids with effective radius $8<R_v<60\,h^{-1}$Mpc and in the redshift range
$0.15<z<0.7$. This could tightly constrain modified gravity scenarios and
models with a varying equation of state, but we identify systematic biases
which must be accounted for to reduce the theoretical uncertainty in the
predictions for these models to the current level of precision attained from
the data. We also examine the distribution of void densities and identify a
deficit of the deepest voids relative to $\Lambda$CDM expectations, which is
significant at more than the $3\sigma$ equivalent level. We discuss possible
explanations for this discrepancy but at present its cause remains unknown.
