  We present a vast landscape of O3/O7 orientifolds that descends from the
famous set of complete intersection Calabi-Yau threefolds (CICY). We give
distributions of topological data relevant for phenomenology such as the
orientifold-odd Hodge numbers, the D3-tadpole, and multiplicities of O3 and
O7-planes. Somewhat surprisingly, almost all of these orientifolds have
conifold singularities whose deformation branches are projected out by the
orientifolding. However, they can be resolved, so most of the orientifolds
actually descend from a much larger and possibly new set of CY threefolds that
can be reached from the CICYs via conifold transitions. We observe an
interesting class of $\mathcal{N}=1$ geometric transitions involving colliding
O-planes. Finally, as an application, we use our dataset to produce examples of
orientifolds that satisfy the topological requirements for the existence of
ultra-light throat axions (\textit{thraxions}) as proposed in
\cite{Hebecker:2018yxs}. The database can be accessed at
https://www.desy.de/~westphal/orientifold_webpage/cicy_orientifolds.html
