Ooh, 0:18 and this sounds pretty promising. I'm not sure if it sounds underwater, but I am feeling the exploration. (Later on, I do get a sort of sunken ship with water dripping)
I would probably recommend a bit less reverb in places, or at least cutting the low end on it because it's kind of muddy when you've got sustains. Those drowned triads are a particular offender. I also probably would not pan all of your instruments quite as hard as that guitar in the left channel.
I don't really have much else to say other than agreeing with Kwing; despite the change of instrumentation later on, which is nice, the theme itself does not seem to progress throughout. It sort of feels like a credit theme rather than a journey in and of itself.
I will say you've chosen great chords to convey mood. I would probably recommend a key change or phrygian mode for a bridge just to switch things up before the final push. Nevertheless, I do see massive potential in you as a composer from this piece alone. Good work!
Thanks for coming out to NGUAC! :)