A protective covering for a swim platform located on a boat is provided. The protective covering may be detachably attached over the top of a swim platform, such as those platforms which are located about the rear of boats or other marine craft. Use of the protective covering will prevent waterfowl or other animals from defecating, loitering or nesting on the swim platform. The covering includes a generally rectangular portion located intermediate a right wing portion and a left wing portion. A plurality of apertures designed to secure the covering to the swim platform are provided on the rectangular portion, right wing portion and left wing portion. Both the right wing and the left wing fold forming a right sidewall and a left sidewall. The sidewalls and rectangular portion form a hollow, generally triangular structure which is placed atop and resides in the area immediately atop the swim platform. The covering is securely attached to the swim platform by any of a variety of attachment means. This prevents any other objects from occupying the swim platform. By extending the length of the rectangular portion, the protective covering may also have application in preventing birds from defecating, loitering or nesting on building ledges.