What type of warning marker is used to warn boaters not to pass between the marker and the shore?

The warning marker used to indicate that boaters should not pass between the marker and the shore is known as a "danger" marker, typically represented by a red and white vertical striped buoy. This marker signifies hazardous areas, such as rocks or shallow waters, where navigation is unsafe. Boaters should heed these markers to avoid potential accidents and ensure safe passage.