CNN —A mysterious patch of fluorescent green water that appeared in Venice’s famed Grand Canal Sunday was caused by a chemical commonly used in underwater construction to help identify leaks, environmental authorities say. Gondolas navigate by the Rialto Bridge on Venice's historical Grand Canal as a patch of phosphorescent green liquid spreads in it, on Sunday, May 28, 2023. Luigii Costantini/APPeople observe Venice's historical Grand Canal as a patch of phosphorescent green liquid spreads in it,. This is not the first time Venice’s Grand Canal has changed color. In 1968 Argentine artist Nicolás García Uriburu dyed the waters of the canal green with a fluorescent dye called Fluorescein, during the annual Venice Biennale.

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