The blue “fire” in the picture is bioluminescence — tiny phytoplankton, microbes washed ashore by the tides, turning their chemical energy into light energy. The process is ancient, natural and found around the world. it’s most easily observed on nice, warm beaches after dark.
“When jostled, each organism will give off a flash of blue light created by a chemical reaction within the cell,” wrote Peter Franks, a biologist at the Scripps Institution of Oceanography, on the blog Deep-Sea News. “When billions and billions of cells are jostled — say, by a breaking wave — you get a seriously spectacular flash of light.” -source