Sonic Man is an aquatic Robot Master who uses small sonar wave attacks that are hard to see. He also attacks with three small mines that he drops directly onto Mega Man. His design is based somewhat off that of Bubble Man and he swims in the same way. He is weak against Dyna Man's Nuclear Detonator weapon because of the rapid change of pressure in the water in causes. Defeating him gives Mega Man the Sonic Wave weapon.