Really nice. Your textures are a lot better, and I liked the sound design.
I felt the sub was a bit too fast, difficult to control, and not like a real sub which is quite slow and has a lot of inertia.
Having a slower sub with slower turning would give more of the underwater feel I think.
LOD distance was a bit short which caused a lot of popup problems. The details, like kelp and seaweed should have made the whole level more interesting, but because i can only see them from about 5 meters away it didn’t stop the level from looking repetitive. You could try using sprites at long distance to reduce processing time, and switch to detailed meshes at close range.
Other than that it was a really big improvement on your last BGMC entry. Good job!