After discussing the previous version of the cave playground conjecture, a class suggestion urged me to explore the ultimate inaccessible print-in-place location: underwater. In this iteration, it serves not as a play space for children, but as one for underwater scuba divers. This is really cool because there is no option to pour or print concrete underwater, so the off-site construction model works really well here. It also serves a genuine need. Currently, dive sites sink random objects like old boats to explore underwater, but these materials could be dangerous to humans and harmful to marine life. Another interesting question: How could this dovetail with my conjecture surrounding concrete as a host for life? Could this structure double as a reef habitat to attract diverse marine life?