What are special marks primarily used for?

Special marks are primarily used to indicate specific areas or features that require attention but do not necessarily fit within the standard navigational aids like buoys or lighthouses. These marks can be used to indicate where weather or data collection activities are occurring. This is critical for navigational awareness, especially when vessels are operating in areas where data is being collected or where weather-related phenomena are being monitored.

In contrast, other options refer to different navigational functions. For instance, identifying hazards would typically be covered by safe water marks or danger marks, while marking restricted areas may use features such as controlled area markers to denote zones where entry is limited or prohibited. Navigation errors are managed through navigational aids that provide correction or guidance, not through special marks. Hence, the primary function of special marks in the context of marine navigation relates specifically to activities related to weather or data collection.