The present invention relates to saddle-riding type watercraft and other small watercraft. In an embodiment, the invention is a small watercraft capable of reducing noise by utilizing the sponson. For example, a small watercraft is provided with a sponson made of synthetic resin, characterized in that within the sponson there has been fixed a weight matched to the frequency of the hull to thereby have a function as a dynamic damper. In an embodiment, the weight is a plate-shaped weight made of metal along the longitudinal direction of the sponson. In an embodiment, the weight is embedded in the sponson along the longitudinal direction thereof.