Casualties Unknown Layers — All 11 Subterranean Depths & Hazard Guide

The subterranean cavern system in Casualties: Unknown is vertically stratified into 11 distinct geological layers descending over 3,000 meters into the planetary crust. Each layer introduces unique environmental threats, ambient temperature zones, exclusive monster spawns, and specialized salvage materials required for high-tier crafting.

Below is the verified master breakdown of all 11 subterranean layers, their vertical depths, environmental hazards, dominant hostile fauna, and essential survival milestones.

Master Overview: All 11 Subterranean Layers

Layer	Depth	Biome / Theme	Primary Environmental Hazards	Dominant Predators	Key Resources
Layer 1: Gravel Lands	0–300m	Damp Sandstone & Shale	Loose ceiling rockfalls, wet cold	Cave Ticks, Scavenger Larvae	Flint, Clay, Iron Scrap
Layer 2: Craggy Crevices	300–600m	Vertical Limestone Chasms	Fatal vertical fall drops, rope snaps	Cliff Striders, Blind Lurkers	Raw Copper, Climbing Tendrils
Layer 3: Dried Desert	600–900m	Arid Limestone & Oil Sumps	9mm Thermal Turrets, Landmines, Dehydration	Sand Burrowers, Stray Drones	Nitrate Powder, Scrap Metal
Layer 4: Fungal Basin	900–1,200m	Bioluminescent Mold Caverns	Hallucinogenic spore gas, damp slippery moss	Spore Walkers, Fungal Leech	Bioluminescent Mucus, Hardwood
Layer 5: Tangled Roots	1,200–1,500m	Ancient Subterranean Flora	Constricting thorn vines, zero light	Snare Vines, Chitin Gnawers	Resin, Tough Fiber, Bone Chunks
Layer 6: Frozen Sinks	1,500–1,800m	Sub-Zero Glacial Crevasse	Severe Hypothermia, fragile ice shelves	Frost Crawlers, Ice Striders	Pure Quartz, Cryo-Ice Blocks
Layer 7: Spore Abyss	1,800–2,100m	Toxic Caustic Vents	Corrosive acid rain, lung necrosis gas	Caustic Leeches, Acid Spiders	Sulfur, Acid Bile, Heavy Shells
Layer 8: Magmatic Seam	2,100–2,400m	Molten Basalt & Heat Vents	Extreme Hyperthermia, lava geysers	Magma Ticks, Fire Lizards	Raw Obsidian, Titanium Ore
Layer 9: Neural Biosphere	2,400–2,700m	Organic Cybernetic Ruins	Brain integrity drain, psychic shock	Synthesized Stalkers, Mech-Hounds	Microchips, Neural Cores
Layer 10: Chitin Catacombs	2,700–3,000m	Massive Hive Burrow	Swarm aggression, pitch-black corridors	Chitin Matriarchs, Swarm Soldiers	Chitin Carapace, Heavy Glands
Layer 11: The Core Threshold	3,000m+	Ancient Precursor Sanctum	Thermal-radiation bleed, crushing gravity	Elder Thornback (Apex)	Precursor Relics, Void Shards

Detailed Walkthrough by Subterranean Depth

Layer 1: Gravel Lands (0–300m)

The starting stratum directly beneath your surface crash capsule. The environment is damp, chilly, and dimly illuminated by scattered surface fissures.

Atmospheric State: Mild hypothermia risk if wet. Groundwater pools require boiling before consumption.
Ceiling Instability: Vibrating sandstone ceilings collapse under heavy walking or melee impacts. Always check overhead when mining flint chunks.
Fauna & Tactics: Cave Ticks cling to dark cavern walls and drop onto your neck, inflicting rapid bleed. Carry a Makeshift Digging Tool and review our Beginner Survival Guide for first-aid fundamentals.

Layer 2: Craggy Crevices (300–600m)

A maze of steep vertical chasms where horizontal footing narrows to razor-thin ledges.

Navigation: Traversing Layer 2 requires at least 4x Fiber Climbing Ropes or Piton Anchors. Falling greater than 6 meters causes compound bone fractures, requiring immediate splinting to prevent shock.
Key Drops: Rich copper deposits used for early electrical circuits and emergency flare casings.

Layer 3: Dried Desert (600–900m)

An arid, fossilized seabed cavern with bone-dry air and abandoned security fortifications.

Thermal Turrets: Automated 9mm sentry guns scan corridors via infrared sensors. Sprinting spikes your body temperature, prompting instantaneous bursts. Crawl prone or throw smoke canisters to break line of sight.
Buried Mines: Rusty pressure plates detonate upon 25+ kg impact. Toss heavy stone scrap 5 meters ahead of your squad when walking across sand drifts.
Hydration Drain: Water loss accelerates by 2.5x. Carry upgraded canteens detailed in our Essential Bags and Containers Guide.

Layer 4: Fungal Basin (900–1,200m)

A sprawling cavern of giant bioluminescent mushrooms and sticky marsh water.

Spore Toxicity: Inhaling airborne spores triggers the Hallucinating and Toxicosis moodles, distorting vision and causing involuntary panic sprints into chasm drops. Wear a Charcoal Filter Mask.
Scavenge Checkpoint: Layer 4 industrial storage caches frequently spawn mid-tier weapon components and rare blueprints.

Layer 5: Tangled Roots (1,200–1,500m)

Thick, petrified tree roots pierce the cavern ceiling, forming dense natural barricades.

Constriction Traps: Stepping on living root creepers triggers rapid snares that immobilize your legs while Chitin Gnawers close in.
Essential Tool: The Gunsaw or a Titanium Machete is mandatory here to carve through thick root walls without draining your entire stamina pool.

Layer 6: Frozen Sinks (1,500–1,800m)

Glacial meltwaters freeze into sheer ice walls and fragile surface crusts over deep abyss pits.

Hypothermia: Ambient temperatures drop to -18°C. Without insulated thermal coats and high-calorie rations, stamina recovery drops to zero within 4 minutes.
Ice Physics: Running on slick blue ice prevents quick turns and causes uncontrolled skids into predator dens.

Layer 7: Spore Abyss (1,800–2,100m)

A nightmarish chasm filled with caustic yellow mist and corrosive fluid geysers.

Corrosive Rain: Caustic drips melt low-durability cloth armor within seconds. Heavy rubber or reinforced composite suits are essential.
Medical Urgency: Chemical burns require immediate neutralizing saline washes. Consult our Medical Trauma & Triage Guide for caustic burn management.

Layer 8: Magmatic Seam (2,100–2,400m)

Open fissures expose molten magma rivers and scalding steam geysers.

Hyperthermia: Character body temperatures rise rapidly, causing heat stroke and dehydration. Water bottles boil and burst unless vacuum-insulated.
Titanium Motherlode: Layer 8 basalt walls contain high-density Titanium ore veins necessary for endgame gear fabrication.

Layer 9: Neural Biosphere (2,400–2,700m)

A surreal biome where biomechanical roots merge with ancient subterranean computer banks.

Psychic Brain Drain: Proximity to neural nodes drains your Brain Integrity metric, causing auditory hallucinations and phantom enemy sightings. Consume Mind Stabilizer tinctures or maintain high morale.
Robotic Fauna: Mech-Hounds patrol in pairs, equipped with shock batons and high-frequency stun blasts.

Layer 10: Chitin Catacombs (2,700–3,000m)

The breeding labyrinth of the subterranean hive colonies.

Zero Light: Natural light sources do not exist. Flares burn out 50% faster due to low oxygen levels. Carry multiple battery packs or heavy chemical lanterns.
Endless Swarms: Combat noise draws endless waves of Chitin Soldiers. Stealth movement and suppressed firearms are critical for survival.

Layer 11: The Core Threshold (3,000m+)

The final frontier of Casualties: Unknown, surrounding the ancient planetary vault.

Apex Boss Encounter: The Elder Thornback roams the vault antechamber with 2,400 HP and heavy chitin plating.
Precursor Technology: Clearing the threshold unlocks endgame blueprints, infinite power cells, and the primary extraction beacon.

Layer Survival Checkpoints Before Going Deeper

Hydration & Caloric Balance: Pack at least 3,000 calories and 4.0 liters of purified water before passing Layer 3.
Medical Triage Readiness: Always keep 3x Tourniquets, 2x Splints, and 1x Antiseptic Salve on your quick-access belt.
Weapon Durability: Ensure your main weapon has at least 80% durability or carry a spare field repair kit.
Console Practice: If you want to test deep layer mechanics in offline sandbox mode, consult our full Casualties Unknown Commands & Cheats Guide.