The Incredible Hulk #174

Feeling a kinship with his irradiated foe, Cobalt Man saves Bruce from drowning in the hull of a sinking ship. As Bruce begins to recover from his ordeal, Cobalt Man decides to destroy the city of Sydney in an effort to show mankind the danger of nuclear power. Betty tries to coax Bruce into turning into the Hulk to face the villain but he has been doped up in the hospital and she has to push him off of the roof to get him frantic enough to exact the change. Cobalt Man tries to defeat the Hulk by flying him to the upper atmosphere but his ploy takes too long and he explodes.