This article is about the Grand Reef. You may be looking for the Deep Grand Reef, the Grand Reef Caves, or the Sea Treader's Path.

The Grand Reef is a unique deep biome in Subnautica that covers a large area in the southern portion of the map.


The Grand Reef is home to many types of fauna, including the large bottom-dwelling Sea Treaders, as well as two Ghost Leviathans. It is also known for its unique types of flora, from the 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 Treaders.

Ruby is commonly found in the Grand Reef, along with many other types of rare crystals.


For a more complete gallery, visit Grand Reef/Gallery.


  • 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.

Spoiler alert: The following section contains story related material.


  1. (Dated January 14, 2016)