People attend The Night of Ancient Bonfires event in Saulkrasti, Latvia on August 27, 2022. During The Night of Ancient Bonfires people light bonfires along the coastline of the Baltic Sea. (Photo by Ints Kalnins/Reuters)

A serviceman of Ukraine's coast guard mans a gun on a patrol boat as a cargo ship passes by in the Black Sea, amid Russia’s attack on Ukraine, on February 7, 2024. (Photo by Thomas Peter/Reuters)

A person dressed as Santa Claus jumps into the sea during the Copa Nadal (Christmas Cup) swimming race in Barcelona, Spain on December 25, 2024. (Photo by Bruna Casas/Reuters)

The sun sets over the Mediterranean sea as a nine-branched Hanukkah menorah (Hanukkiah) is pictured by the coast in Netanya on December 31, 2024. (Photo by Jack Guez/AFP Photo)

A woman walks into the ocean as a sea lion makes its way to the beach in the La Jolla neighborhood of San Diego, California, on September 3, 2025. (Photo by Mike Blake/Reuters)

Horse riding along the beach at Frinton-on-Sea in Essex, UK on Sunday, November 30, 2025 as the sun was setting, Becky James riding Ayla. Photo by Kevin Jay/Picture Exclusive)

A photo taken on July 22, 2017 shows beach- goers dancing at the West Sea Barrage beach outside the coastal city of Nampo, southwest of Pyongyang. The West Sea Barrage beach features as a stopping point for foreign tourists, and is a destination for North Korean work groups from the neighbouring area. The beach lies at the end of an eight- kilometre- long barrage that separates the sea from the Taedong River, which runs through Pyongyang. (Photo by Ed Jones/AFP Photo)

Those lights are actually bioluminescent shrimp, better known as sea fireflies, or, in Japan, as “umibotaru”. Visible every year from May until the end of October, they live in the sand around very shallow sea water and are often seen floating between the extremes of high and low tides. Here: Bioluminescent sea fireflies glittering like diamonds on the rocks and sand. Okayama, Japan. July 2016. (Photo by Trevor Williams/Jonathan Galione/Getty Images)