King Orin did not wish to spread false hope to the people of Poseidonis, so he made sure to keep Thorne’s work a secret. Orin volunteered to test the serum on himself first. The serum worked, and Orin was able to leave the domed city and survive beneath the ocean. The experiment was a miraculous success and Orin quickly dispensed the serum to everyone in Poseidonis, transforming them into an amphibious species.
Thorne was an Atlantean scientist who invented a serum that altered an Atlantean's physiology, enabling them to survive underwater.