Sub-Mariner #24, April 1970. Cover art by John Buscema and Johnny Craig.
Just in case you were thinking about watching Shark Week, it's not what it used to be. It's literally all about shark attacks and it's no longer about shark conservation. Most of the stories on there are bogus anyway, like this one about a giant, super smart, man-eating shark called Submarine who stalks boats then flips them over to eat the people inside. It's all made up for ratings, though some of them are true