The waters in Venice's main canal turned fluorescent green on Sunday. This shocking phenomenon was caught on camera by onlookers and many posted pictures and videos on social media.
The bright green area stretched from the Rialto Bridge to part of the Grand Canal. The verdant blob was first noticed around 9:30 am CET (3.30 am ET) and grew slowly, according to multiple images posted on social media, which showed gondolas, water taxis, and water bus boats skimming through the emerald substance.
Italy's fire department also posted a video of the phenomenon on their Twitter account, in which one of its boats sailed on phosphorescent waters.
Authorities in Venice, are investigating the patch of fluorescent green water. Italy's fire brigade tweeted that they were assisting with providing "samples and technical assistance" to the ARPA Veneto, the regional agency that oversees the environmental state of the Grand Canal, which are "conducting analysis to establish the nature of the substance in the water."
But the mysterious green liquid does not pose a health threat to people in Venice, local police were quoted as saying by Italy's ANSA news agency.
This is not the first time Venice’s Grand Canal has experienced a color alteration.
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. The move was designed to bring attention to ecological issues and the relationship between nature and civilization.
The curious coloring comes as the city is celebrating the Vogalonga boat event, created to combat wave motion, restore Venetian traditions, and help spread attention for the environment and nature, as well as the architecture Biennale, which opened last weekend.