I played this a long, long time ago (sadly, in this galaxy). I've been looking for a working copy ever since. All hail GOG, masters of my soul!
The gameplay is excellent (if not perfect.) Underwater poses some interesting challenges to moving around and the way weapons work. It's fairly standard, but it does throw some twists your way.
The story is. . .well, it's your typical giant monster lifeform of death underwater apocalypse story, but it is encased so well, that you won't notice most of the cliches.
The graphics were, for the time, beautiful. I love being underwater, and this simulates it well.
All in all, a dated, moderately cliche, alright playing game.
I will never love another game as much as I did this one.