Underdog (1964)

Season 1: Episode 26

After being captured by the evil monarchs of Maldemare, Polly and the Professor are taken in front of them and learn of their evil plan. Polly begins to cry for Underdog but is told that he can't hear her down there. Meanwhile, the Navy who was monitoring the expedition, become worried when they lose contact with the bathysphere and Polly and the Professor. They immediately send a message to Underdog who immediately arrives on the scene. Underdog then goes beneath the sea but is monitored by the Empress. She instructs her guards to release the man-eating sharks. After fighting the sharks, Underdog is then grabbed by the 'guard', a giant octopus. Weaken by his fight with the sharks, and almost out of air, he is succumbed and taken to the city where he is thrown into the giant clam with Polly and the professor.