Subnautica 2 Underwater Caves: All Cave Systems and Resources

Underwater Cave Systems Overview

Underwater caves are some of the most rewarding and most dangerous locations in Subnautica 2. These submerged cavern systems thread beneath the seafloor, hiding rare resources, unique flora, precursor ruins, and creatures found nowhere else. They are also claustrophobic, pitch dark, and easy to get lost in, which makes preparation essential before you enter one.

Cave entrances are scattered across every biome. Some are obvious openings in cliff faces or the seafloor, while others are hidden behind kelp or rock formations. Many caves have multiple entrances and exits, forming networks that connect different parts of the map. Mapping these connections is a major exploration project that pays off in resource access.

Every cave has its own ecosystem. The lack of sunlight means bioluminescent flora and fauna dominate, casting eerie glows across the walls. Cave-dwelling predators like crabsquids and cave crawlers are common, and some caves are nesting grounds for larger creatures. Always scout an entrance before committing to a dive, and never enter a deep cave without a clear exit plan.

• Caves hold rare resources and unique creatures.
• Bring lights, oxygen, and a repair tool.
• Many caves connect to other biomes.
• Scout entrances before committing.

Cave Resources and What to Mine

The primary reason to brave underwater caves is the resources. Many of the rarest materials in Subnautica 2 only spawn inside cave systems, where unique geological conditions concentrate them. Lithium deposits, diamond nodes, and kyanite crystals are all commonly found in caves, particularly the deeper ones. These materials are essential for advanced crafting, including vehicle upgrades and base components.

Quartz and gold also appear frequently in caves, along with copper and titanium outcrops. Some caves contain sulfur deposits, which are needed for specific recipes and are nearly impossible to find elsewhere. Gel sacks, a valuable flora used in advanced crafting, grow exclusively in caves -- grab samples and bring them back to a growbed for farming.

Precursor ruins are sometimes hidden inside caves, particularly deep ones. These ruins contain ion cubes, data terminals, and unique blueprints, so cave exploration is tied directly to story progression. When you find a precursor structure in a cave, scan everything and note the location with a beacon, because you will likely need to return.

Cave Navigation and Safety

Navigating a cave safely requires the right gear and the right technique. Light is your first priority -- a flashlight or the Seaglide light is mandatory, because caves are completely dark. A scanner helps you identify resources and creatures in the gloom. Most importantly, drop a trail of beacons or use a string of flares so you can find your way back to the entrance.

Oxygen management is critical in caves. Unlike open water, you cannot simply swim up to the surface -- you must retrace your path to the entrance. Always calculate your oxygen budget for the round trip before you go deep into a cave. If you have a Seamoth, park it at the entrance with a beacon so you have a guaranteed oxygen refill point and an escape vehicle.

Cave predators are a serious threat. Crabsquids disable your electronics with EMP pulses, so turn off lights and tools when one is near. Cave crawlers swarm in groups and can overwhelm you in tight spaces. Sandsharks and other ambush predators hide in cave sediment. Move slowly, listen for audio cues, and keep your repair tool ready for vehicle damage. The repulsion cannon is excellent for cave defense, because it pushes creatures back without needing room to swing a weapon.

Never enter a cave you are not prepared to leave. If you get lost, do not panic -- retrace your beacon trail or follow your flares. If all else fails, swim toward any faint glow, because cave exits often let in a sliver of light from the open ocean.

Major Cave Systems and Locations

Subnautica 2 features several major cave systems, each with its own character and rewards. The shallow cave networks beneath the safe shallows and kelp forests are beginner-friendly, containing sulfur, quartz, and small resources. These are good practice for learning cave navigation before you tackle the deeper systems.

The jellyshroom cave system is a mid-depth network known for its glowing mushrooms and the presence of crabsnakes. It contains lithium, magnetite, and sometimes precursor fragments. The entrance is typically found in the grassy plateaus, and you need a Seamoth or high-capacity oxygen to explore it fully. Watch for crabsnakes, which hide inside the mushrooms and ambush passersby.

The deep cave systems leading to the lava zones are the most dangerous and most rewarding. These connect to the lost river and the inactive lava zones, where kyanite, nickel, and precursor ruins await. You need a Prawn Suit with a depth module and grapple arm to navigate these safely, because the terrain is vertical and the creatures are lethal. These caves are the path to the endgame, so approach them only when fully equipped.

• Shallow caves: sulfur, quartz, practice.
• Jellyshroom caves: lithium, magnetite, mid-tier.
• Deep caves: kyanite, nickel, endgame path.
• Lava caves: extreme danger, top resources.