The Bixby Creek Bridge is one of the highlights of Big Sur, a region along California's coast known for its scenic views.
But a bioluminescent phytoplankton bloom there has made the area outshine other attractions, with the blue glow in the water bringing in a touch of magic on Monday night.
"It is almost certainly a dino-flagellate bloom," Dr Steve Haddock, a bioluminescence specialist at the Monterey Bay Aquarium Research Institute, told the KSBW television station. Dinoflagellates are a group of organisms that include marine plankton.
Dr Haddock said the species behind the recent bloom include some of the usual suspects such as Noctiluca, Lingulodinium and Protoperidinium. The light these organisms emit comes from chemical reactions taking place inside their bodies.
Dr Haddock said the bloom was likely the result of a combination of high nutrient rates and calm conditions that allow high concentrations of dinoflagellates to accumulate in the water.
The organisms will likely disperse once the winds get stronger again.