As lifeguards, we have a few different flags, each with a different meaning. Every flag indicates a different safety situation. Each morning, we estimate what the situation is and hang up a flag accordingly.
The red-yellow flag is raised when the sea is relatively safe. Beware, the sea is never completely safe. The breakwaters are often not very visible and can still hurt your feet.
The yellow flag indicates that there is a dangerous sea. There can be strong currents or big waves.
Single red flag
The singel red flag means that there is a very dangerous sea. The currents are very strong and big waves. Do not go past ankle depth into the sea. If you go further the sea will pull you out into the sea.
Double red flag
The double red flag is raised when you are forbidden to go near the water. There might be a thunderstorm coming. Do not go near the shore line because lighting can still affect you if you stand on the wet sand!