Coral reefs support the most diverse assemblages of marine life on Earth, yet are declining due to local and global stressors. Rapid and widespread monitoring is essential for tracking ecosystem responses, but assessment of coral communities traditionally relies on time-consuming visual estimates of coral cover, the percentage of substrate occupied by living corals. The analysis of environmental DNA (eDNA), free DNA from filtered seawater, offers fast and efficient insights into the abundance and distribution of species, yet it remains untested to monitor coral biomass. In our recent paper, we demonstrate that visual estimates are highly correlated with the abundance of coral eDNA on reefs in Hawai'i measured with a relatively simple, rapid, but replicated PCR-based metabarcoding approach. Careful primer selection and target sequence lengths play an important role in determination of coral abundance from eDNA biomass. Given its broad applicability and ease of use, eDNA metabarcoding can provide complementary analytical support for biomonitoring programs and management initiatives tracking changes in coral cover caused by climate change and other disturbances on coral reefs.