One type of marker is used to warn boaters no to pass between the marker and the shore What color is this marker?

The marker used to warn boaters not to pass between the marker and the shore is typically a red marker. These markers indicate areas that are not safe for navigation, such as shallow waters or hazards. In the United States, they are part of the lateral system of buoyage, where red markers usually denote the right side of a channel when entering from the sea.