Was this scenes like this in the movie?

<<First one they're swimming and some giant tentacle thing is in the water with them but it's very brief and it is never seen again..>>

The "giant tentacle thing" could be the moray eel, but it's seen twice in the movie. Once during the night dive when David goes off by himself while Treece plants the explosives. Then it's seen again at the end, munching on Louis Gossett Jr's head. Also, it's apparently the moray eel that grabs onto Gail's stick and pulls her into the wreck during the opening scene.

<<Jacqueline Bisset is sitting down on a bench and one of the bad guys I think grabs her knees and forces her legs apart.. No idea why but I remember them doing this to her. >>

Yeah that's there. They're checking to see if she's hidden the ampule that David found in the wreck in her unmentionable area.