What must be done when operating a vessel in a designated swimming area?

When operating a vessel in a designated swimming area, the primary safety concern is the presence of swimmers. The correct action is to refrain from operating the vessel in that area altogether. This ensures the safety of individuals swimming who may not be aware of an approaching vessel, as well as providing a clear space for recreational swimming activities.

Operating a vessel in such areas could lead to accidents or injuries, given the unpredictable nature of swimmers and their movements in the water. The rules governing designated swimming areas are in place to protect both the swimmers and the boat operators, preventing potential collisions or hazardous situations.

The other options suggest ways to navigate in or around a swimming area, which could still pose risks to swimmers and are not in line with the regulations typically established in these zones. This highlights the importance of respecting designated swimming areas for the safety and well-being of all waterway users.