How to Break Rocks and Boulders in The Last Caretaker

Large O2 grenades. In the skill tree and your inventory the item is called Large Grenade; the crafting list calls it O2 Big Explosive. Nothing else breaks the big rocks that block caves and hidden rooms.

Petrol grenades do nothing to them, not even the big ones or several at once. Only the O2 ones work.

Hitting and dismantling do not work either. A crowbar leaves no mark even after an hour of swinging or 30,000 points of damage, and the Dismantle Tool cannot take them apart.

Two, as a rule. Two Large O2 grenades cleared the rocks in the Amen vault room and the boulder under a Spire statue, so for all three Spire caves bring six.

Placed right against the boulders, one can be enough. The rocks beside the Amen gate take two or three.

Drop them against the foot of the big rock, not on top of it or a few steps short, then run: the blast hurts you too.

If the rock still will not break, move the smaller loose rocks in front of it back against its base and try again: that is what finally worked after ten wasted grenades.

The small loose rocks in front can be picked up and moved by hand; only the big ones need grenades.

The recipe unlocks at level 19 in the skill tree, where it is called Large Grenade.

Crafting it uses oxygen, so the Fabricator needs an oxygen supply. Without one, the job takes your parts and then just sits on “waiting”; connect an oxygen generator to the Fabricator and it finishes.

Each one takes a Storage Cylinder, a Grenade Ignition and a Nano Mesh, plus 30 seconds at the Fabricator.

A small Portable Oxygen Generator is enough. Once your grenades are made you can take it apart again to get its materials back.

Some lie around ready-made, 19 in all: five at Exodus Station, three at Central Warehouse Alpha, two at Talon Offshore Proving Deck, and one each at North Bastion, the North Bastion Transfer Gate, North Deep Intake Station, two habitat nodes and a few gyrocopter platforms.

Under the statue on top of each of the three Spires is a small cave, its mouth blocked by a boulder. The one at the Spire of Industry holds two Quantum Crystals and some cash.

At Quarantine Stack Amen (about 146, -38 on the map), once the vault door is open, two boulders by a broken wall on the left hide a secret room; you can see the green glow of a Quantum Crystal through the gap.

Inside are three Quantum Crystals and a robot in a chair at a panel with a large red button, which plays a message.

Amen has more. Rocks a little up and to the left of the gate open another way in, so you can skip the climb; more rocks inside the big tunnel hide ore, resources and memories; and the secret caves at Quarantine Stack Chorus also need O2 grenades to break their walls.