ABSTRACT: Efforts to measure tropical marine biodiversity often experience challenges due to the inaccessibility of marine habitats, limited funding available for monitoring programs, and unavailability of staff. Remotely operated underwater vehicles (ROVs), are becoming more popular as a tool for conservation by increasing monitoring capabilities when coupled with image-based surveys, and new, mini-ROVs have reduced the cost for managers. This study compared the use of inexpensive mini-ROVs to snorkel-based field surveys of coral reef benthic organisms and fish in Fiji, where remote accessibility, limited access to SCUBA, and calm, clear environments make ROVs a potentially useful tool. Species richness and community composition for benthic organisms like coral, sponges, and echinoderms and for fish species were compared between methods using generalized linear models, nMDS plots, and species accumulation curves. In situ measurements performed better than ROV-based image datasets, finding consistently higher levels of species richness for both benthic species and fish (in situ richness counts were 159 and 137% higher respectively), but ROV-based image analysis of benthic percent cover was a more accurate estimator of species richness according to species accumulation estimates. Further advances in mini-ROV affordability may make these methods better able to capture higher levels of species richness, but future studies should consider testing ROVs to monitor coral bleaching or habitat loss.