This command allows you to speed up and slow down the day/night cycle. Use 'daynightspeed 1' to restore usual day/night cycle speed.
daynightspeed [multiplier]
| Multiplier | The number you wish to multiply the speed of the day/night cycle by - 2 would make day/nights pass twice as fast, 0.5 would make them last two times longer. |
daynightspeed 1
The above command sets your game's day/night cycle speed to Subnautica's default.
daynightspeed 0.5
The above command would make the day/night cycle be twice as slow as usual (days would go by 0.5x as fast, as would nights).
daynightspeed 2
The above command would make the day/night cycle be twice as fast as usual (days would go by 2x as fast, as would nights).