Surfers paddle their way through waters tinged with red tide off Yuigahama beach in Kamakura, Kanagawa Prefecture, on May 6. (Kenji Notsu)

KAMAKURA, Kanagawa Prefecture--A blue bioluminescence in the waters off the popular Yuigahama beach gave off a supernatural glow on the night of May 6 here, to the amazement of spectators.

The otherworldly phenomenon was caused by an invasion of noctiluca plankton in the waters of Sagami Bay.

Earlier that day, a broad swath of red tide formed off the beach, which was caused by the mass generation of noctiluca and other species of plankton.

According to Enoshima Aquarium in Fujisawa in the prefecture, noctiluca plankton, containing luminous material called luciferin, emit light when they come into contact with the edge of the surf or the sand of beaches.

Part of the plankton's body is tinged in a pale pink hue.

Red tide is triggered by the outbreak of plankton that occurs when seawater temperatures rise to between 16 degrees and 22 degrees and diatoms that the species feeds on flow into the sea from rivers. Red tide can be hazardous to marine creatures as it depletes the nutrients in the water.