Very playable here:
Have been playing with these settings and so far so good. The landscape/horizon bug is well know, as is the lightning bug (some objects render different shadow values)
Tried today and found out that the option ambient occlusion does render differently per eye, so i turned it off and then the color option to “film” which makes the colors way more intense.
After playing a little i would like to add:
Medium quality does not only change the textures but does also simplify the models big time (most noticeable with round objects). So i prefer to play on High.
This game is really beautiful and very immersive. I am looking foreward to foveated rendering with eyetracking and a next gen gpu and i will blow my mind 
Maybe the successor (which is in the works) does not need PP anymore. I really hope so.
Yep, one of the main problems of the game is the lack of advanced options to enable or disable single things.
Also, the game use megatextures tech, which is why we must use medium settings, but we will have lesser tessellation on objects, as mr.uu pointed out.
I tagged @SweViver initially because in his big Pimax review, he had a section on Subnautica, and mentioned accessing some hidden settings. I was hoping he would elaborate in here.
There was recently a thread on the Subnautica subreddit that showed how you can greatly reduce popin by editing a text file.
I just can’t get over this rendering bug/issue. I will say it’s only present near the surface (safe shallows, kelp forest). When I go deep it’s gone and glorious on the 5k+.
Such a nice game, VERY addicting.
I mean, there’s not enough titanium in that sea for my habitats.
Also, triple checked and can’t see substantial visual quality difference between low and high occlusion setting, so i left it in low for now.
Your screen shot looks exactly what I see with my Pimax 4K, Odyssey, Odyssey + and my 8K BE. It’s annoying but luckily one really doesn’t need to see that view very much.
Do you have the weird rendering though? I think I focused too much on the head tilting issue that what I’m seeing must not still be coming across. When my head isn’t titled and I look off at the kelp forest in the background, it looks weird. I can deal with that if it were just the kelp forest, unfortunately I’m also seeing reefbacks, gasopods, and other terrain this way, which is this weirdly shaded silhouette that has glows oddly because each eye has a different color to it. Rotating my head causes the shading to go away (in one eye only).
I only have this problem on the Pimax. Rift, Odyssey, and Odyssey+ do not exhibit this problem (although the Odyssey headsets do have the weird horizon glitch which is minor).
Everyone here is either not seeing the same thing I am, or are oddly OK with it whereas I think it’s game breaking. I’m really hoping it’s the later. I shouldn’t be seeing the shadow of a reefback glowing in my immediate view when the thing is too far away and shouldn’t be rendered at all.
occlusion does render different shadows per eye. this is why i turned it off. i played for 40hrs with it on low and yesterday i was next a rock and saw that there is an issue with the shadow. then i closed one eye and in each eye i saw a different rendered shadow. try it.
i turned it off and then the Color Option to “film”. Looks really great now. and no wrong occlusion Rendering.
The “horizon bug” does render weired models in diestance which should not be seen. That is correct. IT was and is not a “dealbreaker” for me.
anyone also notices that smooth Rendering when turning with headmovement compared to stutter when turning with the Controller?
first i thought it is a controller-bug of the game, so i tried to turn with the mouse - same result.
Then i focused on the White gaze-ring (your “crosshair” for selection. Turn gaze Control on in Options) and then i saw smooth Rendering of the ring when turning with the Controller and a wobbling ring when turning with the head.
Which tells me that when i turn my head some pimax atw is kicking in and makes the turning seem very smooth, but you see the distortion on the gaze-ring from atw warped Frames. On the other Hand, when turning with the Controller the world stutters, but the gaze-ring stays perfectly round…
How come that atw can destinguish between head- and controller-movement? I do not want to see stutter! please smooth all Frames!
Amazing find, the shadow/shade bug is really annoying.
Also, i found VR Enhancements at Subnautica Nexus - Mods and community
I will test these tonight.
Have you found the underground river, yet? There’s a lot of resources down there!
Not yet, still have many upgrades to go to be able to get deep down.
I can barely dive 100 meters and already have to go back to get more oxygen.
Also, anyone knows how i can counter the explosive fish ? Everytime i hear his screeching i start panicking 
I finished this game a long time ago… but I plan to replay it now with my Pimax… I never found a counter besides RUNNING… it never really bothered me that much… but whenever I heard… “It is your primary objective to swim closer to that beautiful creature…” … then I really panic and run because that sucker makes me really nausea in VR.
Yep, it´s a goddamn nuke that follows you.
Thinking about it now… there isn’t exactly a counter but as you progress there are things that will mitigated it. I won’t spoil it for you.
Take your knife and kill him before he explodes
For those who would have this game installed on HDD you can dramatically improve the average fps by putting the save folder of the game on a ssd using a mklink (look for symbolic link), or installing the whole game on a ssd of course, but the save folder is enough if you only have few remaining room on your ssd.
That is if the game developper hasn’t fixed that since I was playing it a few months ago now.
Also know you can heavily compress your (huge) savegame files if you want to make backups.
Swim clooooseeeerrr 
Good find! just tested for a couple of hours and it plays better!
The auto-sort-lockers… is a must have mod!!! That feature should have been built into the game!!!
Also… I used the app VoiceAttack… which I found very helpful when using VR. Voice command so I don’t need to find a keyboard make things much easier. When I played with samsung VR… I found that I needed to center my view a lot… it was just easy to say “center” than trying to find the keyboard command with a HMD on my head.