Subnautica Below Zero is the next chapter in Subnautica story. Players who play it will still be in planet 4546B. Since this DLC is in Steam Early Access, the total play hour is around 4 to 5 hours depending on how fast you play the game. The rest is just filled with bugs without much playable gameplay.
You will still find yourself in the vast beautiful oceans of the alien planet while trying to get resources to supply yourself, build bases, Submersibles, anything that you would do in the original game. Given that Subnautica: Below Zero is around $14,99, you will not get much out of it but this always has been the way the developer company Unknown Worlds Entertainment approaches their titles. It is certain that if you purchase Subnautica: Below Zero, you will get more out of your money over time.
However, it is best to wait if you don’t like waiting for development time in games and like to finish everything all at once. As it’s mentioned above, the play hour is roughly 5 hours and of course, it comes with lots of bugs that need time to be fixed but after all, that’s what Steam Early Access is all about. Stay tuned for more updates on Subnautica’s only DLC Below Zero!