Hydro-Man can transform any or all of his body into a coherent watery mass. Hydro-Man can use this for a variety of effects including firing jets of water, increasing the water pressure within his body, changing his shape, elongating himself or growing to immense size by dispersing his mass, and absorbing ordinary water to heal himself or to add to his mass. While in aquatic form, Hydro-Man is superhumanly strong and nearly indestructible by conventional means, although is susceptible to various heat-based and sponge-like attacks.
Morris Bench, formerly a crewman on a cargo ship, was accidentally knocked overboard by the hero Spider-Man while a powerful experimental generator was being lowered into the ocean for testing. Exposed to the energy conversion process of the generator while being bombarded with volcanic gases, Bench's cellular structure was altered. When he was rescued from the depths, his body began exuding great quantities of a watery substance Bench first thought was perspiration. Annoyed by the incessant dripping, Bench went to a local pub to stir up trouble. Finding none, he was astonished to learn that he could convert his entire physical form into a watery liquid. He then set out to find those he held responsible for his condition and make them pay. Adopting the name Hydro-Man he embarked on his criminal career.