So the main rundown (although I hate numbers)
Graphics: 4/5
They are nice to look at and there is some variety in it.
Sound: 3/5
I like it for most part. I do not get tired or annoyed by the music, which is rather relaxing in my opinion. There could be more variety for the death sounds, and the sound of the submarine engine simply sounds silly. Something what iffs me out about it.
Replay value: 2/5
There is nothing much to replay or do, once you have achieved all. There fun runs dry once you achieved anything.
Other (nitpicking in progress):
For me, who likes the story, behind the gameplay, it is something odd that there isn't a flimsiest pretext as per why are we killing animals (what somewhat wounded the me as an animal lover. Why animals? But I am nitpicking here) and why do we try to get as deep as possible? There's a similar game based about rocket building. It has that what I mentioned. You haff motive for doing all that there, but I cannot see it here, and I do not believe it would of been arduous task of making any pretext for all the mentioned. I doubt that science is being performed by torpedoes either, IMO.