TOKYO - Officials were left red-faced at a beer factory in Japan's Okinawa region on Tuesday, after a mishap turned a large body of water a sinister shade of scarlet.
A leak filled a port area in the city of Nago with the lurid-coloured water, which one Twitter user described as looking "venomous".
Orion Breweries said water used for cooling, which contains a liquid called propylene glycol -- dyed red with food colouring -- had leaked from a factory in the area.
In a statement, it apologised for "causing enormous trouble and worry".
"We believe the leaked cooling water seeped through rainwater gutters into a river, and consequently turned the ocean red," the company said.
The red water poses no danger to humans or the marine ecosystem, the Yomiuri newspaper also quoted the company as saying.
Okinawa is a subtropical island chain famed for its crystal blue waters, and is popular with scuba divers.
"The red does look venomous, but it's a relief to learn it's just food colouring and not likely to cause major damage," wrote a Twitter user under the name Aresu.