I first saw The Abyss on Sunday, 24th January 1993 on Channel 4 in the UK. They mistakenly broadcast the film uncut for which the governing body, OFCOM, slapped their wrists.
Not long after, the Special Edition had a UK release on VHS, which I would snap up instantly. Although, I would be amazed at the terrible editing used to hide the rat in the infamous scene where they force it to breathe oxygenated liquid.
In 2000, I would import the two disc DVD from the US which was fantastic, but the only setback was the picture was non-anamorphic. This didn't worry me too much at the time because I was watching on a 14-inch portable.
Finally, after waiting over two decades, I finally have the film in HD and 4K! It's been so long, it's skipped a generation. ๐ Plus, I had to import the film from the Netherlands as it isn't getting a release here in the UK!
Essentially, that's why it's not got a release in the UK.