Hello Kindertrauma! It's Popcornmonster.
I recently had a very Kindertrauma-esque moment I would like to share. A little background and then I'll explain the solution to the mystery.
When I was five years old, so this would have been around Summer of 1979, I vaguely remember playing with a friend who lived a few houses away. We were in the basement of his house and a puddle had formed on the floor from the washing machine. We starting pretending it was a lake. Then my friend started telling me about some new movie where the people can't go in the water because the water comes alive and eats the people. Some time later, we were walking past the TV and the trailer was playing for the film. My friend pointed it out to me and said that was the movie he was talking about.
Fast-forward thirty-five years. Long time horror fan and filmmaker myself now. But I've never known what that scary movie was. I knew it wasn't Jaws or Piranha. The time period doesn't match up and I knew what Jaws was. So a few nights back I was watching Machete Maidens on Netflix. It's a documentary about how cheap it was to make exploitation films in the Philippines during the late 60s through the early 80s. When suddenly they played a trailer for a film. I immediately recognized that trailer from that dusty old memory and now I had a title to go with it. A title that IMDb verified with the June 1979 release date. The film was "Up From the Depths", which now I realize was a title that sat under my nose all these years. The poster artwork was a familiar site in the old video stores but I never bothered to see the film. Until last night.
It's one of the dopier Jaws clones of the late 70s. They even managed to copy the mayor from Jaws with an arrogant idiot resort owner that refuses to heed the danger. The goofy kill scenes all look like the actors flopping around in a pool while someone bubbled red dye around them.
Ultimately it's a dumb movie but now it holds a place in my memory for being "that movie".