The movie terrified me, but boy, did I ever enjoy it. It gripped me...everyone remembers this part of the movie:
When that shark came out of the water, I involuntarily jerked my hand back so hard that I whacked the guy sitting in the seat next to me. He didn't even notice.
After the movie, a big group of us went back to my family's house to go for a swim in the in-ground lighted pool, and it was probably ten at night. I couldn't believe it. I actually felt nervous swimming in a lighted swimming pool at night!
The next night, we all went up to a lake to play a prank on a guy we knew...we were going to swim across a lake (maybe 300 yards) and sink his little dinghy...we weren't going to damage it, just let the water in and sink it. As we swam across that New England lake that night, with the moon shining down, glittering on the water, I was as nervous as a long-tailed cat in a room full of rocking chairs.
It was completely irrational. But I was nervous. And then my buddy started thrashing around saying something was biting him, and I hissed at him to shut up, mainly because he was bugging me out!
Now, when I was a kid, I lived in the Philippines for several years, and I lived in the ocean during that time, every chance I got. I had no problem at all swimming at night in tropical waters twenty feet deep. Contemplating that a just four years in the past scared me just thinking about it after seeing "Jaws".