I remember watching a BW sci-fi tv movie from the 70s with two marine biologists (man and woman) doing a routine reconnaissance in a mini-sub similar -but smaller- to the Proteus from the 1966 Fantastic Voyage. They were being chased and wrapped up by a kind of Kraken. The scientists used robot arms and small torpedoes to defend themselves from the beast. Finally, the scientists get help from a bigger submarine that blasted with high precision the sea monster who fled back to the black depth of the ocean. Anybody knows what movie is this?
I think this may be It Came from Beneath the Sea
When more people are attacked and killed, the Defense Department authorizes Mathews to take out the submarine and fire the torpedo