The Charlie Flag is a maritime signal flag used in the International Code of Signals. It is represented by a blue and white checkered pattern and is used to indicate that a vessel is in distress or requires assistance. When displayed, it alerts nearby ships and authorities to the situation, prompting them to offer help. In addition to its distress signal, the Charlie Flag can also signify that a ship is conducting underwater operations. This warning is crucial for ensuring the safety of other vessels in the vicinity, as it informs them to navigate with caution around the area where the flag is displayed.