Inactive Lava Zone

The Inactive Lava Zone is a large, cavernous biome located 960 meters below the surface. It is the second deepest biome and the penultimate area in Subnautica.

Overview

The volcanic rock which has formed in this area can be carbon-dated to between 800 and 3,000 earth years ago. ― PDA, when approaching the Lava Castle

Description

The Inactive Lava Zone is characterized by large, arching structures and walls of hardened lava with occasional steaming lava falls. It is composed of two distinct areas and can be found at 960 to 1390 meters down, well below the limit of a Seamoth (even when equipped with a Seamoth Depth Module MK3). This makes an upgraded Cyclops and Prawn Suit the only vehicles able to navigate through it.

The player must be extremely careful when navigating this biome. Touching the lava on the floor completely depletes health in seconds, and the temperature applies constant damage unless the player wears a Reinforced Dive Suit. The biome contains the rare resource Kyanite, used in crafting Prawn Suit and Cyclops modules. Due to its high temperature and abundance of lava, a distinct reddish fog shrouds the entire area, limiting vision.

Access is possible through two entry points in the western and eastern wings of the Lost River: the Mountains Corridor and the Tree Cove, respectively.

Overview of the Inactive Lava Zone Chamber

The Inactive Lava Chamber

At the center of the Inactive Lava Zone is a large chamber featuring occasional veins of lava and spires of hardened rock.

Resources and Features

• Spires: Contain Titanium, Copper Ore, and Ruby.
• Lava Rivers: Narrow corridors around the area contain Silver Ore, Crystalline Sulfur, and Diamond.
• Lava Castle: A large structure in the middle of the chamber.
• Volcanic Domes: Small, partially-collapsed domes scattered across the floor may contain Ruby, Magnetite, and Gold.
• Reaper Skeletons: Many skeletal remains are found here, as Sea Dragon Leviathans hunt them and bring them to the central chamber to feast.

Near the Lava Castle, multiple lava falls lead directly into the Lava Lakes. These can be found by following streams of molten lava on the floor of the Chamber.

Flora and Fauna

• Resources: Copper Ore, Crystalline Sulfur, Deep Shroom, Diamond, Gold, Kyanite, Large Copper/Gold/Lead/Quartz/Silver/Titanium/Uraninite Deposits, Lithium, Magnetite, Nickel Ore, Quartz, Ruby.
• Creatures: Crimson Ray, Lava Larva, Lava Lizard, Magmarang, Red Eyeye, Sea Dragon Leviathan, Warper.

A Reaper Leviathan Skeleton

Small Lava Geysers

Transition from Lost River

Lava river near the Lava Castle

Lava falls leading to Active Lava Zone

Sea Dragon Leviathan

View of Lava Falls

Entrance to Active Lava Zone

The Inactive Lava Zone Corridor

The Inactive Lava Zone Corridor is a small section linking the Lost River and the Inactive Lava Zone. There is only one such corridor accessible via the Tree Cove. The other entrance in the Mountains Corridor leads directly to the main Inactive Lava Zone and the Lava Castle.

These corridors are characterized by large cavernous spaces of hardened lava with veins of active lava that sometimes eject molten boulders. The corridors converge into the central chamber.

Resources

Nickel Ore and Crystalline Sulfur are frequent here, useful for vehicle upgrades.

• Resources: Crystalline Sulfur, Diamond, Gold, Large Copper/Kyanite/Lead/Titanium Deposits, Lithium, Nickel Ore, Silver Ore.
• Creatures: Lava Larva, Magmarang, Red Eyeye, Warper.
• Flora: Deep Shroom.

Lost River Inactive Lava Zone Corridor

Deep Shrooms

The Lava Castle

The Lava Castle is a special area within the Inactive Lava Zone. Its entrance is located in the Lost River Mountains Corridor.

It is a huge structure of volcanic rock with a large interior cavern, obsidian pillars, and thermal vents. Various cave systems lead to a central chamber featuring a lava pool surrounded by tall rock spires. The structure appears to be the breeding ground for Lava Lizards, as their eggs are only found here.

Although the exterior formed naturally, data downloaded from the Alien Thermal Plant suggests the Precursor Race excavated much of the interior. The Alien Thermal Plant is located inside the castle.

Resources

• Resources: Crystalline Sulfur, Kyanite, Lava Lizard Egg, Magnetite.
• Creatures: Lava Lizard, Magmarang, Red Eyeye, Warper.

Exterior

Entrance marked by pillars

Interior

Lava streams

Magma bridge

Alien Thermal Plant

Rock formations under Thermal Plant

Smoke FX

Concept Art

The Lava Pit

The Lava Pit is a large pit on the outskirts of the main chamber. A low, fractured lava dome sits at its center, surrounded by towering lava drip columns. Deep grooves run between these columns; one groove on the northern edge provides an entrance to the Lava Lakes.

Unlike the rest of the Inactive Lava Zone, the lighting in the pit is cooler and brighter. Notably, raw materials normally found in Harvesting Nodes can also be found naturally loose on the seabed here. This is the only location where resources like Titanium or Gold appear in this loose state.

Resources

• Resources: Diamond, Gold, Large Uraninite Deposit, Lead, Lithium, Magnetite, Quartz, Titanium.

The Lava Pit

Inside view

Giant Lava Dome

Entrance to Lava Lakes

Another view of the Lava Pit