Spider-Man Season 2 (1968) EP5 - Menace from the Bottom of the World

Investigating the disappearance of banks (which have been mechanically submerged to deep inside the Earth), Spidey finds a hole that leads to a maze of underground tunnels, through which Spidey undertakes a perilous journey in search of the lost occupants of the submerged banks, and he comes upon a bizarre city populated by group of Molemen led by a maniac intent on conquest of the ""surface people"", some of whom- the occupants of the banks-the Molemen are holding prisoner.