Abstract: A marker for use by boaters to mark spots in a body of water includes a water-tight, hollow cylindrical main body that floats and which serves as a buoy member. The main body is capped at its opposite ends by end caps that are apertured. An elongate hollow tube is positioned within the hollow interior of the cylindrical main body so that it extends between the apertures. A spool member having a preselected length of line coiled thereabout is rotatably mounted atop the upper end cap and line extends from the spool through the interior of the hollow tube to the bottom of the body of water when the marker is in use, there being a weight at the free end of the line. Beads of progressively larger size relative to the free end of the line are secured to the line, each bead being positioned at a preselected length of the line that represents a particular water depth.