- "Enlightenment awaits you...under the sea!"
- —Jacques Douteux promoting his exhibit
Enlightenment Under The Sea was one of the exhibits in the Hill Valley Science Expo. It was hosted by diver Jacques Douteux and featured a bathysphere in a large tank of water. Entering the bathysphere required a ticket.
During the Science Expo, Citizen Brown took on Douteux's apparel and hid his younger self - whom Brown had rendered unconscious - in the bathysphere.
Marty McFly, looking for Brown, recognized the voice behind Douteux's helmet and, realizing what had happened, attempted to expose him. After attempting to pull off "Douteux's" helmet and then requesting that the bathysphere be raised, Marty stepped on the tube of air leading to the bathysphere. This lead to a standoff in which Brown, feeling the effects of his younger self's lack of air, refused to raise the bathysphere and Marty, who had much at stake, refused to uncrimp the hose. Eventually, Brown had no choice but to raise the bathysphere in order to keep himself from suffocating. But while Marty pulled Brown's younger self from the bathysphere, the older Emmett made his escape, fleeing the expo.