This is a report of the field investigation on submarine sand banks and large sand waves at the Bisan Strait in the Seto Inland Sea. Soundings, collection of bottom materials, and observation of tidal currents constitute this investigation. The floowings have been made clear by the investigation.
(1) Northern part of the sand bank is flood-dominated current velocity zone and southern part is ebb-dominated zone. The sand bank is formed by the above mechanism of the tidal currents.
(2) As tidal currents flow aground onto the sand bank, intensity of turbulence increases and two prominent eddies appear. After they pass over the sand bank, intensity of turbulence decreases and those eddies disappear. It seems that sand waves are formed due to the above changings of the internal structure of tidal currents.
(3) Submarine sand waves are dunes. These scales are approximately equal to the values which are calculated by Yalin's formula.
　This report has been translated into English as a following report. Ozasa H: Field Investigation of Large Submarine Sand Waves, Coastal Engineering in Japan, Vol.17, Japan Society of Civil Engineers, 1974