NEPTUNE FACTOR 1966 (FOX)

Interesting and well made film about a team of three men who are working in an underwater lab who suddenly find themselves lost in a weird underwater world after an earthquake throws the lab into a cavern deeper under the ocean than anyone has ever gone.
Topside, a group of scientists take a small underwater craft called Neptune to new depths to find the lost men and run into a world where man is easily the smallest creature there.
Ben Gazzara, Ernest Borgning, Yvetter Mimieux, and Walter Pidgeon star in this exciting film that is sure to please sci-fi buffs and adventure fans as well.