Voyage to the Bottom of the Sea (1961)
Probably the best Irwin Allen film that I've seen. The plot is complete hokum and the special effects are excellent. It was great to see Walter Pidgeon, Forbidden Planet is probably my favorite film, and Michael Ansara though I felt his role was superfluous. Like 20,000 Leagues Under the Sea this film features its own fight with a giant squid though I believe the former looked better on screen. I know they made a television series based on the film, I'll probably check it out.