Abstract: A marker buoy for marking a particular spot on the bottom of the sea despite heavy seas. The buoy includes a hollow cylindrical chamber whose outer surface forms a spool. A length of line is attached to the chamber and wound around the spool with an anchor attached to the free end of the line. An elongated hollow tube is attached in axial alignment to one end of the cylindrical chamber. A cored foamed polystyrene ball whose diameter is slightly greater than the diameter of the cylindrical chamber is slidably mounted on the elongated tube. A cap affixed to the free end of the tube prevents the floatable ball from sliding off the tube. The buoy is placed on the surface of the water with the axes of the chamber and tube parallel to the water's surface. Small holes in the chamber gradually fill with water as the line runs out following the descending anchor.