Does Subnautica: Below Zero take place on the same planet as the original?

Subnautica: Below Zero is a wonderful survival game that takes place on a fictional planet known as Planet 4546B.

Planet 4546B gets its name from the nearby star that it orbits, 4546. The B comes as a designation that it is the first planet classified as such near the star. Planet 4546B is almost entirely covered in water.

Players of the first Subnautica game will recognize this planet. It remains the location of the series in Subnautica: Below Zero, as a planet used by The Architects to conduct their research on the Kharaa bacterium.

Note: Spoilers ahead for the plots of Subnautica and Subnautica: Below Zero.

---

Planet 4546B in Subnautica

Image via Unknown Worlds Entertainment

The original Subnautica takes place in the late 22nd Century. Humanity has just begun to colonize other star systems. The player is a crew member of the ship Aurora.

The crew's objective is to create a high-speed space travel infrastructure, but as it arrives in the system some mysterious energy pulls it to the planet below. The Aurora then crash lands on Planet 4546B.

The crew, aside from the player, perish when trying to escape the crash. The player learns of the Precursors, later known as the Architects, and their weapon that shoots down any ship leaving the planet.

This is to halt the spread of the Kharaa bacterium from Planet 4546B to elsewhere in the universe. This weapon is what caused the crash of the Aurora and a ship they were secretly sent to find the Degasi.

---

Planet 4546B in Subnautica: Below Zero

Image via Unknown Worlds Entertainment

Subnautica: Below Zero takes place two years after the events of the original Subnautica. Planet 4546B is pretty much the same water-filled planet that it was in the first game.

The big difference is the existence of Alterra on the planet. After the first game, Alterra Corporation built base after base on the planet in order to study the planet. Prior to the game, they removed all personnel from the surface.

Players take on the part of Robin Ayou, who smuggles herself onto the planet to investigate the suspicious circumstances of her sister Sam's death. During this, Robin comes into contact with the consciousness of an Architect.

The Kharaa bacterium is much more prevalent in Subnautica: Below Zero, with the player given the option to cure a Frozen Leviathan of the disease. It seems this is what disrupted Alterra and humanity from colonizing Planet 4546B.