Listen at about 5:50 to around 6:00 in the video clip. What does the music sound like to you? You may have to listen to it a few times if you don't recognize it the first time.
The film itself is "The Sea Serpent" (1984) and this is just one part of it.
Edit: You're free to watch as much of it as you want, of course. I just wanted to point out that particular moment.
I don't recognize that musical passage.
Destructive critter, though.
When I listened at that particular moment, the strumming music chords reminded me of the music score from "Jaws."