This command can be used to change your view distance. Note that some users have reported it does not work for them. Use 'farplane 1000' for default view distance.
farplane [view distance]
|View Distance||Your desired view distance, 1000 being the default view distance.|
The above command sets your view distance to Subnautica's default. If you have not changed your view distance before, this shouldn't change anything.
This command sets your view distance to 2000. This is double Subnautica's default view distance, meaning you should be able to see further into the distance. You may have more lag as a result of this.
This command sets your view distance to 500, which is half of the default view distance - you will not be able to see as far into the distance, but may have increased performance/FPS as a result of this.