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The Grand Reef is a deep biome in Subnautica which covers a large area in the southern portion of The Crater.


The Grand Reef is home to many types of fauna, including the large bottom-dwelling Sea Treader Leviathans, as well as two enormous Ghost Leviathans. It is also known for its unique types of flora, from the many luminous Anchor Pods to the peculiar Membrain Trees. There are many entrances to small caves known as the Grand Reef Caves in the Grand Reef. Scattered deep within the Grand Reef are multiple hydrothermal vents.

Below this area, the player can find a large cavern system featuring the similar types of flora and fauna, with the addition of Crabsquids and Jellyrays and the absence of the Sea Treader Leviathans.

Rubies and Gel Sacks are commonly found in the Grand Reef, along with many other types of rare crystals.

Spoiler alert: The following section contains story related material.

One of the five Sea Emperor Juveniles can be found here after the Sea Emperor Leviathan Eggs have been hatched.



  • In earlier builds, the Grand Reef had large pillar-like spikes, some of which were visible above the surface. These were removed and was explained to be temporary. However, the concept of them may have been used for inspiration of the Crag Field. Another reason for their removal is that they had bad models and were not destructible.[1]
  • Certain structures have curious house-like caverns, very reminiscent of grotto-homes in primitive cultures.
  • The Grand Reef is the third biggest biome in Subnautica.
  • Despite its name, the Grand Reef does not have actual corals nor any reef-like structures at all.
  • There are actually only 3 types of Flora in the Grand Reef: Anchor Pods, Gel sacks, and Membrain Trees.

Spoiler alert: The following section contains story related material.


  1. (Dated January 14, 2016)