With summer time, holidays and time to enjoy the beach life, it is very important you know the meaning of the local flags on the beach.
Here is a classic example, the courtesy of “Protección civil” from Manilva:
Green = Safe to bathe
Yellow = Bathe with caution especially with children
Red = NO BATHING _ DANGEROUS CURRENTS OR WEATHER CONDITIONS
White = Jellyfish warning
Black = Closed beach