|This article is about the Underwater Islands. You may be looking for the Floating Island or the Mountain Island.|
The Underwater Islands are a unique biome in Subnautica, featuring many massive rock formations suspended above the ocean floor. Bonesharks dwell abundantly here, along with other types of fauna and flora. It also features its own cave system, the Underwater Islands Caves.
Most of the Underwater Islands rely completely 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 the largest island, while Lava Geysers can 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. In some places, small streams of sand can be seen flowing down from over the edges of the islands.
Quartz is a common find on both the tops and walls of the islands, with Diamonds occasionally as well. Sandstone Outcrops and Shale Outcrops are located on the ground of most of the islands. Large Resource Deposits of Uraninite and Silver are located at the bottom with the Lava Geysers. Large Gold Deposits are rarely found near the cliffs around the biome, alongside Limestone Outcrops and Spadefish.
The Underwater Islands border one of the Mushroom Forests, 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"