What navigational aids guide boaters along their course?

Buoys and markers are essential navigational aids used by boaters to safely guide them along their course. These physical structures are placed in navigable waters to indicate important information such as safe passage routes, hazards, and various navigational instructions. For example, they can show the boundaries of safe channels, alert boaters to nearby hazards, or denote specific areas such as no-wake zones or restricted areas.

While traffic lights and signs and signals might be relevant for roadways, they do not typically apply to water navigation. GPS systems also play a crucial role in navigation, providing digital mapping and positioning, but they are not physical aids placed in the water. Therefore, buoys and markers represent the most traditional and direct method for guiding boaters on the water, making them the correct answer in this context.