Underground Caves are one of StarRupture’s most important points of interest. They’re time‑limited, easy to miss, and they hold materials you can’t reliably get anywhere else. The catch is that every entrance is wrapped in living vines that only clear for a few minutes at a time.
Everything about them is built around the planet’s Rupture cycle: the wave opens the caves, the regrowth closes them, and you work in the narrow window between.
Where Underground Caves are and how they appear on the map
Underground Caves sit under mid‑sized patches of overgrown vines scattered around Arcadia‑7. On the surface, they look like shallow, organic craters covered in thick greenery you cannot mine, shoot, or blow up.
Once you have the world map unlocked through your chosen corporation and access to a Corporate Terminal in your Habitat, caves begin to show up as you explore. Activating a Geo Scanner reveals large sections of terrain at once, including these cave spots.
Initially, each cave appears as a question mark. As you move closer, the icon resolves into a small circle that marks the entrance area. That circle is the warning that a vine‑covered pit is either beneath your feet or very close by.
Early on, players usually spot their first cave near the Orbital Lander, either around the calcium ore patch to the north or to the south on the way toward the toxic green biome. There are at least ten distinct cave locations in the current map, with more likely as the game expands.
How Rupture Waves control cave access
On a normal day, Underground Cave entrances are completely sealed. Grenades, weapons, and even mining beams do nothing to the vines that block them. The only reliable way to open a cave is to use the planet’s own reset button: a Rupture Wave.
When a Rupture passes, the surface is blasted by lethal heat and radiation. All visible plant life, including the cave vines, is burned away in the process. As the world cools into the “dark and dusty” post‑wave phase, those entrances are briefly exposed as open pits.
Life on Arcadia‑7 grows back extremely quickly, in a matter of minutes. That regrowth recloses the caves. The usable window is short enough that you usually manage one or two caves per cycle at most, depending on how close they are to your shelter and how fast you move.
How to prepare a cave run
Because the timing is tight, planning ahead matters more than raw gear. The basic loop is: locate a cave, build nearby, wait out the Rupture, then sprint straight to the hole.
Step 1: Unlock and use the map. Reach corporation level 3 to enable the world map at the Corporate Terminal in your Habitat, then explore until you reveal at least one cave marker. Triggering a Geo Scanner helps uncover several at once.
Step 2: Physically visit the cave to confirm its exact location. Walk up to the vine‑covered depression so the map switches from a question mark to the cave’s circular icon. Mentally note landmarks for navigation in low visibility.
Step 3: Build a small base as close as you safely can. At minimum, place a Habitat to survive Ruptures, plus some storage so you can dump materials and go in light. The goal is to minimize travel time between safety and the entrance.
Step 4: Stock up for one sprint, not a long expedition. Bring enough food, oxygen, ammo, and a functional Harvester, but avoid overweight inventories that slow you down. You are racing the planet’s regrowth timer more than fighting enemies.
How to enter an Underground Cave after a Rupture
Once your base is set and a Rupture is imminent, everything revolves around leaving the Habitat at the right moment and running a straight line to the pit.
Step 1: Wait out the Rupture inside your Habitat. Stay put while the external temperature spikes. The moment GAL indicates conditions have dropped back to an acceptable range, prepare to leave.
Step 2: Exit during the dark phase. As soon as it is survivable outside but still dark and dust‑filled, leave the Habitat and head straight to the cave you marked earlier. Do not stop for surface resources; every second you spend wandering is one you lose inside.
Step 3: Confirm the entrance is open. When you arrive, the heavy green vines that covered the depression should be gone, revealing a vertical pit with pale, dead vines hanging down the walls. If you see fresh green growth, the window has already closed, and you’ll need to wait for the next wave.
Step 4: Climb or drop in. Use the white, desiccated vines as a ladder to descend safely. If you’re confident in your movement, you can carefully drop and use your boost near the bottom to cancel fall damage.
The entrance remains open while the world is still in its Rupture aftermath. As soon as the planet “comes alive” again and surface vegetation starts to return, the vines regrow over the hole, and you are on the clock to get out.
What you find inside Underground Caves
Underground Caves are compact networks of tunnels that house several resources that are either rare or entirely unique to this environment.
- Glow Cap appears as tall, yellow, fungal plants that emit a soft light. These can be harvested by hand.
- Quartz Ore forms as blue crystal clusters in the rock walls and floor. You mine it like other ore nodes.
- Corpse sites and loot sometimes appear as skeletons of calcinated colonists, often with items like tech components, consumables, or special currencies such as War Bonds nearby.
Glow Cap and Quartz feed directly into late‑game crafting. They are used for recipes such as Quartz Building Material and multiple “Res Plasm” consumables that improve resistance to various hazards, including Drain, Termo, Infection, and Corrosion. They can also be turned into Data Points if you need a fast reputation bump with corporations.
Movement inside the caves is more about navigation than combat difficulty:
- Crouch to access low tunnels and small pockets where extra Glow Cap or Quartz may spawn.
- Use your boost to hop up short ledges and cross uneven terrain quickly.
- Keep your flashlight on; the Rupture aftermath outside may provide some ambient light, but the deeper branches are very dark.
Because caves only stay open for a few minutes per wave, it usually isn’t worth leaving anything behind. Scour every reachable branch once you’ve learned the layout; efficient paths make future visits faster.
How long caves stay open and how many you can run per wave
The usable window for each cave follows a predictable pattern around the Rupture cycle.
- After a Rupture, the cave opens when the surface cools enough to be survivable, while the world is still dark and barren.
- As soon as vegetation starts to regrow topside, the entrance vines return and the hole reseals.
- In practice, you get only a few minutes per cave between first entry and full closure.
With smart base placement and a direct route, you can typically clear one cave thoroughly and sometimes chain into a second nearby cave before the world fully resets. Pits are spaced far apart, so more than two in a single cycle is unrealistic without future changes to the map.
Players who tried waiting inside caves for the next Rupture confirmed two important points: you are not protected underground when the next wave comes through, and no extra items or special spawns appear during the period when the entrance is sealed. The only reliable benefit is the short resource window after each wave.
How to leave an Underground Cave safely
Leaving a cave is simple if you pay attention to the entrance state and keep an eye on the planet’s regrowth. Problems start when you lose track of time and find the exit covered again.
Step 1: Return to the entrance before full regrowth. As soon as you notice the outside sky brightening or see fresh vines encroaching on the rim, stop looting and head back to where you dropped in.
Step 2: Climb the dead vines if the hole is still open. When the entrance is visibly clear, walk to the wall where the pale vine “ladder” hangs and climb out.
Step 3: Use the red bulb to force an opening if it’s sealed. If you arrive and find the pit covered, look for a red, bulbous node in the vine mass near the entrance. Equip your Harvester and attack that red node until the vines retract and the shaft re‑opens.
Step 4: Climb out immediately. Hitting the red bulb only buys a short reprieve, roughly twenty seconds, before the vines close again. Start climbing as soon as you see the gap, and do not stop to loot anything else on the way.
Optional tricks and edge cases
A few behaviours around caves sit at the edges of the main loop but are worth keeping in mind.
- Grenades at the entrance have, at times, been able to force a briefly open hole when thrown directly on top of a sealed cave. This behaviour has been seen during earlier testing and may not be consistent.
- Sliding into surface vines can occasionally drop you into the pit even when the opening is hard to see, especially if there is a small exposed gap in the foliage. This is unreliable and not a substitute for Rupture timing.
- Glow Cap restocks every wave. After each Rupture, previously cleared caves will spawn new Glow Cap and Quartz nodes, making them repeatable but still constrained by the time window.
Underground Caves are deliberately inconvenient, but that friction is what makes Glow Cap, Quartz, and the occasional War Bonds feel valuable. Treat each Rupture as a scheduled mining expedition: map your nearest pits, build the right shelter, and move fast when the planet lets its guard down.
