I have a really good Subnautica survival world at the moment, and I have been playing it for a few weeks now. But in order to get it working I had to stop it from crashing. And as I had no worlds the method I tried was "-forced3d9". And it worked!
I was able to build a base and All of the vehicles until I forgot about it crashing.
But all of a sudden today it started acting up again, so I retyped the code into the launch options, and cleared the caches (which is a silly temporary fix) I even reinstalled the game, and nothing seems to work. I doubt the problem would have to do with terraforming too.
So, I can play the game with it crashing at regular intervals (but that's no fun), or I can keep trying to fix it. If anyone would like to help or if the developers could fix it, much thanks would be given!
Oh, and my friend who play's Subnautica is also struggling with the issue. Which would make this a double thanks.