Thunderball

The fourth entrant to the Bond series, Thunderball provides one of the best songs of the series but arguably Connery's worst.
Thunderball sees James Bond on a mission to retrieve two atomic bombs stolen by SPECTRE. The simple recipe of the early Bond films is followed except for one major adjustment - almost a quarter of the film takes place underwater!
It is as if the technology to film in such a location only just became available. While I like the use of the harpoon as a weapon - accompanied by the line "I think he got the point" - the film felt like it was never going to end. 
The villian wasn't too bad, but Number Two - or Emilio Largo by his real name (played by Adolfo Celi and voiced by Robert Rietty) finds greater fame over 30 years later when Austin Powers is released.
Add to that an almost comical climax where the boat on which they're fighting seems to be sailing at a an enormous speed - and over the same area until an explosion - and it's simply tacky as far as I'm concerned.

Thunderball: 130 minutes
Bond Song: Thunderball by Tom Jones, Mr Kiss Kiss Bang Bang by Shirley Bassey