The Marvel Super Heroes

Prince Namor the Sub-Mariner #4 - Atlantis Under Attack; The Sands of Terror; The Iron Idol of Infamy (1x17)

Air date: Sep 23, 1966

Attuma steals the sacred trident of Neptune and kidnaps Vashti. Namor follows but it's just a distraction so Attuma's armies can attack Atlantis.