A red flag is posted on Jones Beach in Wantagh, New York, in 2021. / Credit: Howard Schnapp/Newsday RM via Getty Images As with many things, red indicates hazards on the beach. The U.S. Lifesaving ...

When this flag is up, weak swimmers should refrain from going into the water, while others should exercise "enhanced care and caution." As with many things, red indicates hazards on the beach.

More information: Masaki Shibata et al, Do red and yellow flags indicate a danger zone?: Exploring Japanese university students' beach safety behaviour and their perceptions of Australian beach ...