Sure, I think the pacing is generally fine, if not a bit slow in the shallow zones. It would be neat if there was more to differentiate the zones instead of just color/light level.
It might be because the sea creatures are all pretty alike other than looks/hitbox, so it starts to feel a little stale in the shallow zones after several consecutive runs. Maybe the creatures could have distinct movement patterns that make the early zones more interesting? Or maybe allow the diver to progress faster if you keep them towards the bottom of the screen?