For the option, see option#boulder.
Item Classes
" Amulets [ Armor
% Comestibles $ Coins
* Gems ! Potions
= Rings ? Scrolls
+ Spellbooks ` Statues and Boulders
( Tools / Wands
) Weapons
` Boulder
Name boulder
Appearance boulder
Cost 0 zm
Weight 6000

A boulder is a huge stone, represented by ` by default (customisable through the boulder option). Although technically considered items, they behave differently from other items in many ways. If you move onto a square containing a boulder, you will try to push it to the next square in line. If this fails, you will be unable to enter the square, unless your inventory is almost empty (except for gold). Pushing boulders exercises the player's strength, and can be used as a "gym" to make a weak character stronger.

Non-phasing monsters cannot enter a square containing a boulder, except for giants. Giants may stand over and pick up boulders and throw them. A boulder thrown at you ends up on your square, and you may move off it as normal, but cannot re-enter the square without pushing the boulder out of the way. If polymorphed into a giant, you can do the same.

Boulders block line of sight. Monsters cannot attack through boulders, but you can use missile weapons, wands, and spells to attack through them. Wands of striking or spells of force bolt will shatter boulders, but other wands and spells (specifically the wand of digging) will pass over them with no effect on the boulder.

Boulders can be used to block corridors, doorways and pits. Boulders are especially useful for crossing water: push them into water and they will create new dry land for you to walk (9/10 chance). If the boulder sinks without a trace, just try again with another boulder.

Boulders are sometimes found in traps, where there is a hidden switch that triggers a rolling boulder, that may crush the player. They can also be summoned by using a scroll of earth. To get past a boulder, the player may break it into stones with a pickaxe, wand of striking or force bolt. It is also possible to take off all armor, drop enough (most) items from the inventory, and squeeze past it.

A spell of stone to flesh turns a boulder into a huge chunk of meat, which is a normal item with none of the boulder's unique properties.

Many players choose to change the symbol for boulders to make them more noticeable, particularly during Sokoban. 0 (zero) is a popular choice.

Boulders are often used to protect stashes by pushing one on top of the stash or even many boulders around it as a fort.

Tactics for pushing boulders Edit

Slashem boulders

Four of the boulders in this screenshot were blocking the long corridor, but through deft squeezing and pushing the hero pushed them into rooms. If that boulder in the lower-right had started at that position, it would likely be part of a boulder trap.

If you push a boulder, then it will move to the opposite square. In the diagrams below, the # represents where the boulder will move. (Boulders in Sokoban never move diagonally.)

@     @     @       #     #     # 
 `    `    `   #`@   `    `    `   @`# 
  #   #   #           @   @   @

If there is no space or if it is occupied by a monster (whether hostile, peaceful, or your pet) then you cannot move the boulder in that direction. Failing to push a boulder will consume a turn if there is a wall behind it, but not if there is a monster behind it. If your inventory is mostly empty, you can squeeze onto the square containing the boulder. (The fastest way to drop your inventory is to press D and then choose option "A" to drop all items.) Such squeezing is useful if there is a door, hidden space, or boulder on the other side.

If a monster blocks the other side and will not move away, you have the option of squeezing onto the boulder and fighting it bare-handed and naked, or you can throw ammunition or fire wands past the boulder. The player below might want to toss darts, rocks, or other objects at whatever is blocking the way to some holes ^ in Sokoban.


You can move diagonally around boulders (but not in Sokoban). So the following boulder does not block your path provided that you know how to use [yubn] or numpad to move diagonally:


If a boulder is blocking a corridor, and if you are able to push it into a room or into a position like the above, then you can walk around it.

When faced with two consecutive boulders in a corridor, as shown below, you can squeeze past one to push the other.


However, wandering around naked with no wielded weapon, or allowing hostile monster to take from your inventory, might put you in too much danger. You might want to push the other boulder and retrieve your inventory quickly. (The fastest way to retrieve the inventory is to press @ to toggle autopickup on and then move onto the square where you dropped it. Then you might want to press @ again to toggle autopickup off.)

Boulders, like anything else, cannot pass diagonally through open doors. If you need to do that, destroy the door by closing it with c and then kicking it down with Control-D.

The two boulders below are stuck against a wall, and you may only push them in two directions:

-----------          ------ 
|...`.....|          |....|    ------- 
|.........|     #####..`...####......| 
|.........|     #    ------    |.....| 
---.-------   ###              -------

If a boulder becomes stuck in a corner, then you can not move it at all, even if you squeeze onto its square (unless you are able to dig around it). In Sokoban, a 2x2 square of four boulders (or a 2x2 square of both boulders and walls) is almost likewise stuck, but you might be able to squeeze yourself to free the boulders. (Squeezing causes a luck penalty in Sokoban.) Outside of Sokoban you could have freed a boulder by moving it diagonally, but not if you have two boulders stuck against the same wall.

----     ----     ......     ...|..   
|`..     .``.     ..``..     ---`.. 
|...     ....     ..``..     ..``.. 
                  ......     ...... 
    stuck         stuck in Sokoban

Be very careful in Sokoban to not stick boulders in the above manners unless you are able to solve the level with the remaining boulders.

Boulder creationEdit

A user has suggested improving this page or section as follows:

"clarify how fast monsters dig, if tame dwarfs dig, boulder generation probability, and if it matters if the monster digs intrinsically (all hulks, woodchuck, rock mole) or with a tool"

  • Sometimes, a newly created ordinary level will contain randomly placed boulders.
  • Rolling boulder traps always have a matching boulder.
  • Sokoban levels have boulders in fixed places. See Sokoban for special properties.
  • Giants and titans will often have a boulder in their starting inventory (except if reverse genocided).
  • Digging monsters will leave boulders on roughly 7% of all tiles of diggable rock they burrow through.
  • Reading a scroll of earth, depending on the scroll's BUC status.
  • Polymorphing statues will sometimes produce boulders.
  • You can wish for one boulder at a time.

In the endgame except for the Plane of Earth, only polymorphing statues, randomly spawned giants, and wishing are sources of boulders.

Encyclopedia entryEdit

I worked the lever well under, and stretched my back; the end
of the stone rose up, and I kicked the fulcrum under. Then,
when I was going to bear down, I remembered there was
something to get out from below; when I let go of the lever,
the stone would fall again. I sat down to think, on the root
of the oak tree; and, seeing it stand about the ground, I saw
my way. It was lucky I had brought a longer lever. It would
just reach to wedge under the oak root.
Bearing it down so far would have been easy for a heavy man,
but was a hard fight for me. But this time I meant to do it
if it killed me, because I knew it could be done. Twice I
got it nearly there, and twice the weight bore it up again;
but when I flung myself on it the third time, I heard in my
ears the sea-sound of Poseidon. Then I knew this time I
would do it; and so I did.

[ The King Must Die, by Mary Renault ]

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