Abstract: A small, lightweight, reusable marker buoy is provided for marking a selected location on a body of water. The marker buoy has a buoyant float formed with an upwardly open well within which is mounted a rotatable anchor line spool. A conduit directs anchor line from the spool, through the float body, and out the bottom of the float where it is attached to a weighted anchor. A spring biased friction plate within the well provides resistance to rotation of the spool and a nut that secures the spool on an upwardly projecting spindle can be tightened to press the spool against the friction plate with a predetermined force to provide a preselected resistance to rotation of the spool and thus a preselected tension on the anchor line. In use, the resistance is set to allow the weighted anchor to draw anchor line from the spool as the anchor sinks but to resist further deployment of anchor line from the spool due to wave and wind action after the anchor has fully deployed.