This article is about the Underwater Islands. You may be looking for the Floating Island or the Mountain Island.

Erosion patterns on the landmasses suspended here suggest they once floated on the surface.


― PDA, Dialogue


The Underwater Islands are a unique biome in Subnautica, featuring many massive rock formations suspended above the ocean floor. Here, Bonesharks dwell abundantly, along with other types of fauna and flora. It also features its own cave system, the Underwater Islands Caves.


Most of the Underwater Islands completely rely on the buoyancy provided by ancient Floaters. Currently, there are eighteen islands in the area, with the size of the many "islands" varying from minuscule to massive. Two of the largest islands have a great variety of life forms, and even possess their own separate cave system. A large ring of broken-off rocks surround the largest island.

Hydrothermal vents can be found on the surface of some larger islands, with Lava Geysers to be found in huge numbers on the ocean floor directly underneath the islands. Occasionally, large chunks of rock can be seen falling down from the islands and disintegrating into dust. In some places, small streams of sand can be seen flowing down from over the edges of the islands.

Quartz is a common find, with Diamonds occasionally as well.

The Underwater Islands border one of the Mushroom Forest, Mountains, one of the Kelp Forests, and the Northern Blood Kelp Zone. Wreck 4 is located in the Underwater Islands, suspended by two of the islands.

Spoiler alert: The following section contains story related material.

An Alien Vent Entrance Point is found in the Underwater Islands.



  • The PDA suggests that the Underwater Islands once floated on the surface, like the Floating Island.
  • The old Biome ID for the Underwater Islands was "waterislands"