Accessory mounting systems for stand up paddle boards are disclosed. In one example, the accessory mounting system includes a mounting plug secured to a stand up paddleboard, a accessory plate secured to the mounting plug, and one or more accessories secured to the accessory plate. In other examples, the accessory plate is provided with an adhesive backing and can be mounted and secured to the stand up paddle board, thereby allowing the accessory mounting system to be used on boards not having mounting plugs and/or at locations where mounting plugs are not present. In yet another example, a mounting track is provided instead of a accessory plate such that one or more accessories, such as fishing rod holder, can be slidably mounted on the stand up paddle board.