The difficulty of viewing through turbid water-due to obstruction from backscattered rays-is overcome by adopting the range gate camera,which is actuated only during the interval when useful laser signals are reflected from the object illuminated by pulsed laser beam. Laser ray attenuation turns out to depend on suspended particle size in the same turbidity. Experiments are performed to prove ULVS applicability to burial support of NIIGATA MINATO tunnel caissons in the estuary of SHINANO river. Results of trial runs prove appreciable improvement of image quality compared with conventional underwater camera.