The soil particles causing turbidity in the sea compose flocs. The behavior of flocs composed in the sea is different from individual soil particles. The basic knowledge concerning the behavior of soil particles in the sea was gained by observing flocs composed in salt water under the microscope.
　The maximum median floc particle size is proportional to the nearly -0.3～-0.5th power of concentration of SS and to the nearly -0.4～-0.8th power of velocity gradient. Distribution of floc particle size can be expressed Rosin・Rammler distribution. The number of flocs in the unit volume is proportional to the nearly 1.7th power of concentration of SS. The average value of relative floc density is proportional to the nearly -1.3th power of the maximum median floc particle size. The settling velocity of flocs which calculated using Stokes' law exists between 0.001cm/sec and 0.01 cm/sec. The median settling velocity of flocs is proportional to the nearly 0.7th power of the maximum median floc particle size.