It is a very long submarine 3 floors, But 3rd floor looks completely destroyed
3rd floor has only 2 rooms one on far left and far right, middle section is gone

Blue in color
Bottom side has a big turret
Broken in half with back half leaning upward
Top side has 3 turrets - 2 Harpoon turrets one in front one in back and one coil gun turret

The area under the Navigation terminal is 100% inaccessible from 360 even if you destroy the walls there are collision blockers from entering. You will even see a ladder and door that supposed to let you go down but if you destroy it, it is just impossible.

I destroyed the entire 360 around the area and couldn't get inside
The thalamus spawned inside, that zone

I ended up having to keep shooting the empty space until I saw a hitbox and when it went down it died.

The Error Log showed a bunch of errors showing unable to place entity in location with New Wrecks

https://i.imgur.com/BV6c8qj.png
https://i.imgur.com/y24UKQY.png