True, it'd miss some of the cooler effects. But -for once- that'd be realistic( really ) if you have a mission taking part in deeper water, like 100 - 11000m; there are no plants or anything rarely any fishes or other animals, the ground would actually look more like a desert. Remember seaQuest? The deep sea would actually look like that, monotonous and barren, the life takes place in the first few dozen meters at the surface.
But true, for a close to surface mission it'd lack some important elements like proper animation for animals, light effects(though I'd think you could probably simulate that one with some tricks). Theough remember, the sea-life thing was rarely seen even in dedicated submarine games, at least I can't remember seeing it in Aquanox or that older game whose name I forgot) or you could always make something up to explain the lack of animals(were killed by ecological catastrophe/it's actually a sea on another planet etc.)