A Erwin Allen classic "City Beneath the Sea" from 1971, like all his productions, VERY sloppy on the science, but damn, those model effects looked great for the time..
very colorful as well...with massive amounts of techno-nonsense being spouted every 10 minutes. Supposedly, this tele-film was to launch a series, and Mr. Allen was very keen to do it.
But 'twas never meant to be.
Haha I got this via Warners Archive collection. Dig the clothes.
If you like his movies check out When Time Ran Out, it's got an all star cast and lots of Irwin Allen production quirks and set designs