Yes! thanks alot! this is definitely the one. I found the Swedish name for it.
The movie "the Abyss" is called "avgrunden" wich means just 'abyss' or 'chasm'.
and "the rift" is called "sprickan till avgrunden" meaning sort of "the crack to the abyss"
Now when i know the name of it, it will probably be easier to find.
I surely will be dissapointed when I see it as any other movie not seen in about 20 years, but now I just must see it.
Thanks again!