Presentation at 'Discussion with real intention on the Dual-use (of sciences for Peace and War)' on Nov. 25, 2017, held as one of the sessions during the Science Agora 2017 at TELECOM Center Building, Odaiba, Tokyo. It shows to the audience the close relation of Ocean Science with military researches, and activities of voluntary members of the Oceanographic Society of Japan for responding to discussions in the Science Council of Japan.