Subnautica: Lost River - biome guide Subnautica Guide and Walkthrough
Last update: 27 March 2021
It's a vast underground biome that extends under almost the entire map. The entrances to this almost 1000 meters deep zone can be found in the Grand Reef, Blood Kelp Caves, and near the border of Mountains and Bulb Zone. The entrance from Blood Kelp Caves is the only guarded entrance to the location, but by a Ghost Leviathan of all things.
The biome can be divided into 3 sections. Each of them features a similar set of resources, including limestone, sandstone, shale, quartz, ruby, and Nickel. The thing that distinguishes the sections is the danger level of each of them.
Disease Research Facility
This part of the biome contains the ruins of a research complex. Its database will contain information on the origin of Warpers. The facility will also contain an Ion Cube and an egg of a Sea Dragon Leviathan. Additionally, you'll find a complete skeleton of a Sea Dragon Leviathan.
The only danger in this area are the Warpers, but they limit themselves to guarding the ruins of the Research Facility. You won't find any near the skeleton.
Great Cove Tree
A small area in Lost River biome, centered around the Great Cove Tree. Here's also where you'll find the entrance to the Inactive Lava Zone, a biome located directly below.
This area is completely safe. The only creatures inhabiting this location are Ghostrays. This, in addition to the good amount of available resources makes this a perfect spot for a base.
Bones Field
A skeleton of a large, unknown organism towers over this part of the biome. Two entrances to the biome lead through this area.
This part of the biome is largely safe. The only exception is the skull of the dead beast - that region is patrolled by a Ghost Leviathan. Ghostrays are the only other big creature roaming this zone.