Subnautica 2 Exploration Guide: Secret Areas, Hidden Biomes & What's At the Edge of the Map

The main story path takes you through maybe 60% of what's currently on Proteus. The rest is off the critical path. Hidden caves. Alternative entrances. Areas the game never explicitly sends you to. This is where the best content lives.

I've spent more time exploring these side areas than following the story. Here's what I've found.

The Shallows Has Layers

You think you know the starting biome. You've swum through it for five hours. There's more.

Beneath the central plateau at about 120 meters there's a network of interconnected caves. They're not marked. No fragments spawn inside. No story events happen there. It's purely an environmental discovery.

The caves are full of bioluminescent fungi. The water is warmer than the surrounding area. There's a current that circulates through the tunnels. If you follow it, it leads to a small chamber with a single Axum obelisk. No interaction possible. No data to scan. Just an ancient alien object sitting in a cave no one was meant to find.

I've come back to this chamber three times. The obelisk hasn't changed. But I keep checking.

There's also a second entrance to the Shallows cave network near the thermal fissure. Look for a narrow crack in the rock wall at about 80 meters. It's easy to miss. Inside is a larger chamber with several resource nodes and a single data log from a colonist who was hiding from something. The log is short. "They're in the water now. I can hear them clicking. If anyone finds this, don't go deeper."

The Vine Tangle's Hidden Garden

Most players rush through the Vine Tangle to reach the colonist outpost. They miss the best part.

At the northeastern edge of the Tangle, where the vines thin out, there's a small valley at 200 meters. The valley floor is covered in a different type of plant life. Smaller. Denser. Bioluminescent in colors I haven't seen elsewhere. Purple and gold.

In the center of the valley is a pond. Not a water feature. An actual pond of denser liquid that sits on the seafloor. It's brine. Swimming through it damages you. On the other side of the pond is a single Growbed with fully grown Marblemelons. Someone planted them here. A colonist. They've been growing for 25 years, sustained by the nutrient-rich brine.

There's a Beacon next to the Growbed. Labeled "For whoever comes next."

This is the most human moment in the game. No combat. No reward. Just a garden planted by someone who knew they were dying and wanted to leave something behind.

The Trench Back Entrance

I mentioned this in another guide but it deserves more detail.

The main entrance to the Trench is at 350 meters on the western side. A Lurker patrols it. The encounter is manageable but annoying if you're making multiple trips.

The back entrance is at 350 meters on the eastern side. It's a narrow crevice between two rock formations. You need the Tadpole's Scout chassis to fit through. The Cargo and Deep chassis are too wide.

Inside the crevice is a vertical shaft. It drops straight to 500 meters. At the bottom the shaft opens into the main Trench. You bypass the Lurker entirely. You also bypass the first two colonist outposts in the Trench. Don't use this entrance if you need to visit those outposts. Use it if you're heading straight to the Axum facility at depth.

There's also a halfway point in the shaft. At about 420 meters there's a small alcove. Inside is a power cell charger and two Ion Batteries. Someone set up a resupply point here during the colony days. The charger still works if you connect a Thermal Plant to the nearby vent. Free power in the middle of the most dangerous biome.

The Fungal Basin Has a Second Floor

The Fungal Basin is roughly 400 to 600 meters deep. Most players explore the main basin floor and call it done.

Above the basin, at about 300 meters, the fungal growths form a canopy. Dense enough to walk on. If you exit the Tadpole and stand on the canopy, you can look down through gaps and see the Titan below. It's unsettling. It's also functional.

The canopy has resource nodes that don't spawn on the basin floor. Rare minerals. Kyanite. The good stuff. The catch is that you're exposed. Nothing between you and the open water. If something swims up from below, you have maybe three seconds to react.

I found a Thermal Plant blueprint on the canopy. It was inside a small Axum container wedged between two fungal stalks. I've never seen the blueprint anywhere else. Not sure if it's a guaranteed spawn or I got lucky.

The Reef Shelf's Giant Skeleton

At the far edge of the Reef Shelf, past 300 meters, there's a skeleton. Enormous. The ribcage alone is maybe 50 meters long. It's not a Lurker skeleton. Not any creature currently in the game.

The skeleton is old. Partially fossilized. Coral growing through the bones. Near the skull there's an Axum data terminal. The translation is fragmentary but it describes something called "the Song." A creature that the Axum worshipped. Or feared. Or both. The translation is unclear.

Inside the ribcage there's a small cave. The entrance is hidden behind a bone fragment you have to swim around. Inside: an Ion Cube and a Cuddlefish equivalent egg. The egg is the only guaranteed Glowfin spawn I've found.

The skeleton is directly above the Trench entrance. You can see the trench opening from the skull. I think the geography is intentional.

The Void: What's Actually Out There

The Void is the edge of the map. Past 800 meters. Pitch black. Cold. Hostile.

There are Ghost-equivalent creatures out there. The Entity. They're not fully implemented. Their behavior is inconsistent. Sometimes they attack. Sometimes they ignore you. Sometimes they just watch.

I've mapped about 300 meters into the Void before losing my nerve. There are rock formations. Small outcroppings. Resource nodes with minerals I don't recognize. Things that aren't in the crafting menu yet.

At roughly 1000 meters there's a flat plain. Completely barren. No rock formations. No resources. Just flat seafloor stretching into darkness. The sonar on the Tadpole picks up something massive at the edge of its range. Something that moves. Very slowly.

The Void is clearly meant to be the endgame area. The content isn't finished. But the atmosphere is already there. The feeling of being somewhere you absolutely should not be.

I recommend visiting the Void exactly once before the content update. Swim out about 200 meters past the map edge. Sit in the dark for a minute. Listen. Then go back. It's the most effective horror experience in the game and it doesn't even do anything yet.

Areas I Haven't Found

There are persistent community rumors about a biome above the Fungal Basin canopy. Some kind of floating island equivalent. I've searched. Nothing. There might be a subsurface cave network in the Reef Shelf that I haven't fully explored. The Axum vault in the Trench has a door I can't open. The portal in the Void doesn't activate.

Early Access means some of this might not exist yet. Some of it might require items or triggers that haven't been discovered. I'll update this when new content drops.

For now, the secret areas that are accessible are worth the time to find. Not for the loot. For the moments. The garden in the Tangle. The obelisk in the cave. The giant skeleton. These are the things that make Subnautica 2 feel less like a game and more like a place.