Display omitted •Exposition of the DNP mechanism for 13C nuclei in optically pumped diamond with a focus on multi-nuclear Landau–Zener crossings•Features of the DNP mechanism in orientation independence.•New “Hole burning” DNP protocol for high resolution DNP-ESR spectroscopy. The emergence of a new class of optically polarizable electronic spins in diamond, nitrogen vacancy (NV) defect centers, has opened interesting new avenues for dynamic nuclear polarization. Here we review methods for the room-temperature hyperpolarization of lattice 13C nuclei using optically pumped NV centers, focusing particular attention to a polarization transfer via rotating-frame level anti-crossings. We describe special features of this optical dynamic nuclear polarization (DNP) mechanism at low-field, in particular, its deployability to randomly oriented diamond nanoparticles. In addition, we detail methods for indirectly obtaining high-resolution NV ESR spectra via hyperpolarization readout. These mechanistic features provide perspectives for interesting new applications exploiting the optically generated 13C hyperpolarization.