Namor (Vic Perrin) is concerned when his cousin, Namorita (B. J. Ward) falls ill after encountering some pollution dumped by the Kingpin. Naturally, Namor turns his wrath toward the surface, but not before leaving Namorita in the care of Dr. Donald Blake (Jack Angel), the alter-ego at the time of Thor.
Meanwhile, Kingpin is hosting a summit meeting involving old rivals Hammerhead (William Boyett, ex-Adam-12, but virtually unrecognizable in applying a Brooklyn accent) and Silvermane (Paul Winchell, who also voices one of Kingpin's henchmen). Bill Woodson is heard not only as J. Jonah Jameson, but also Dr. Everett, Kingpin's personal scientist du jour.
Here's "Wrath of the Sub-Mariner":
Marvel missed a golden opportunity to give Namor his own series after this, as this could've been a back-door pilot, especially considering 'Nita was flirting with Dr. Blake. Since this series lasted just 1 season (as opposed to Spider-Man & His Amazing Friends, which bowed the same year, getting 3), maybe Marvel decided against it. Their loss.