Sensing this was going to be "one of those", I switched to a viewing perspective that totally rejects reality. Enjoyment levels rise when taking it as a good ol' Italian rip-off as it has many of the hallmarks. Some of the actors appear dubbed, the sets consist of bulky electronics randomly glued onto walls, and some gratuitous gore livens things up. Heads explode, limbs are torn off, monster tentacles tear apart like melons, gangrenous blanders pulse on victims, corpses call out for SOS, and claymation comes in for a few of the creature shots. The bio-suited cavernous gun/monster battles also echo Luigi Cozzi's Contamination (1980). Ultimately inoffensive crap at only seventy-nine minutes; although I'd suggest Antonio Margheriti's Alien from the Deep (Alien degli abissi) as the preferable 1989 trash alternative to The Abyss, Leviathan, and Deep Star Six.
I suspect Shochiku Home Video's VHS was simply taken from the standard English print since it has full English credits. In the same fashion as Grotesque, the Japanese's picture quality has a "baked", eroded appearance presumably compared to its U.S. counterpart. I have yet to see the stateside Live Home Video VHS, but the segmented videos on YouTube and pictures from the tapes around the 'net look vastly better. Shochiku's transfer also seems to have an extremely boosted color cast in many sequences, the cavern shots are GREEN, compared to a completely neutral palette seen elsewhere (like the trailer below).