The Amazing Spider-Man #212 (1981)
“The Coming of Hydro-Man!”
Writer: Denny O’Neil
Artist: John Romita Jr.
Spider-Man again protects the boat where he fought Sub-Mariner in the previous issue. Through an accident while trying to lower a generator under the water, one of the crew members turns into Hydro-Man.
Hydro-Man, after figuring out what he can do looks for Spider-Man to fight.
They meet up for a fight on a rooftop on the hottest day of the year and Spider-Man gets the better of him by creating a chase and making Hydro-Man run through stuff that absorbs a lot of the water on his body. With a punch, Hydro-Man explodes T-1000 style and evaporates.