I suppose for 1961 this film was supposed to be " cool " , but looking back now ( 45 years ) it's charm was just as silly as it's entertainment value ! Granted , the special effects do well on T.V. with the Series that started in 1964 , but for the BIG screen ?? I once had a fish tank that was equally as exciting ! I must agree about the Octopus scene near the end where it attached itself to the Seaview. Obviously not well staged...or trained ! Overall , it's pretty bad acting with shoddy special effects and I still do recommend it - for fun laughs sake. This was probably one of Irwin Allen's Biggest films and I think he thought a lot of it . Barabara Eden went on to play " Genie " on T.V. Micheal Ansara was her Husband . Now that is a cool part about this film ! I always enjoyed seeing real life Husband and Wife teams star in the same movie . Neat !