Sand movement around the submarine canyon offshore of the Morito River mouth on the Seisho coast was investigated by a tracer test using colored sand. Because the sand movement deeply depends on the grain size of sand, colored sand with the grain size of 0.2, 2.0 and 10 mm were prepared and placed on the shoreline. The subsequent movement of colored sand was traced by sediment sampling. It was found that the colored sand with the grain size of 0.2 mm was quickly diffused and part of sand sank into the submarine canyon, whereas the colored sand with the grain size of 2.0 and 10 mm were very stable, and gradually moved alongshore without offshore movement.
