Brief History
Dr. Joseph Jennings of Empire State University was one among several surface humans by which Dr. Hydro/Herman Frayne exposed a derivative of the Terrigen mists which mutated them into the Hydro-Men, amphibian humans. It was Dr. Hydro’s idea of how to ensure the survival of humankind by making it more adaptable.
Dr. Hydro was later killed in conflict with Namor and the Hydro-Men allied themselves with the victor. They were not pleased with their state of life and searched for a cure to their condition. Jennings became their leader and started researching a cure. The Hydro-Men subplot run from “Sub-Mariner” vol. 1 #61 (May, 1973) to “Marvel Two-In-One” #72 (January, 1981). They were at last “cured” by Mr. Fantastic who invented a device negating Terrigen-derived powers