Digging is usually done with a pick-axe, a dwarvish mattock, or a wand of digging. You can also dig if you polymorph into a creature that does not need a pick to use the tunnel attribute (r rock mole, r woodchuck or U umber hulk). Casting the spell of dig has the same effect as zapping a wand of digging.
Digging using a pick-axe or mattock is slow, and takes several turns. Other methods use a single turn.
You can dig in any horizontal direction. You can also attempt to dig upwards and downwards if you use a tool, wand or spell. If you dig upwards, you will be unable to reach the ceiling with a tool, or just loosen a rock from the ceiling and have it fall on your head with a spell or wand.
If you dig downwards with a pick-axe or mattock, you will usually create a pit. To create a pit, you need to apply the tool once. ("You start digging downward. You dig a pit in the floor"). If you dig downwards in a pit, you will create a hole and fall through. Zapping a wand of digging downwards instantly creates a hole under normal circumstances. Digging downward when standing on a sink will turn in into a (non-magical) fountain, and when standing on a fountain will most likely create several pools of water.
The ground or the walls in some levels are undiggable. These include the walls of Sokoban, the ground at the bottom of several dungeon branches, walls of the Castle and the Wizard's Tower, and the like. If the floor is undiggable, digging downwards can create a pit but not a hole. The walls of Gehennom are diggable, but the wand and the spell only dig one wall per casting.
You can dig up rocks, boulders, and statues with a pick-axe or a dwarvish mattock, and chop down non-petrified trees with an axe. The spell and wand of digging instantly generate results and completely bypass this discussion.
Each turn you dig, you generate
9 + d5 + enchantment - erosion + strength & dexterity bonuses + ring of increase damage bonus
points of digging effort. This is doubled if you are a starting race dwarf. The strength & dexterity bonuses are the same as for weapons to-hit adjustment. The pick-axe skill does not play a role.
|Terrain type||Digging effort needed||Examples: expected turns|
|STR=11, DEX=11||and thoroughly rusty||STR=18, DEX=18||and +3 mattock|
|through an existing pit||251||21.4||28.3||15.2||13.0|
|other floor, fountain, sink, any non-pit trap||51||4.8||6.1||3.4||3.0|
|statue, boulder, wall, solid rock, (secret) door; chop down tree||101||8.9||11.7||6.3||5.6|
There is no speed difference between a pick-axe and a mattock; however, mattocks are heavier, two-handed, and can be generated enchanted.
Shop doors and walls will cause the warning message "This door/wall seems too hard to dig." to interrupt you, but will not take any longer to destroy if you persist. Digging through the walls or door is costly, but the floor is free. Shopkeepers have a rough idea how long this takes and will move to prevent theft.
Special cases: Fumbling causes bad effects instead (33% chance). Digging down on an altar is impossible, but would incur the god's wrath and anger any tending priest. On the Plane of Earth, earth elementals can form, and your passage may collape.
Digging monsters are not covered in this discussion.
You can escape by digging downwards and making a hole. You will generally need a one-turn method to dig, such as a wand or spell. Remember that this will deepen your dungeon level, and you might find yourself in a worse position. Monsters will also use this escape technique when they possess a wand of digging, which can be aggravating.
You must cross solid rock to access the portal on the Plane of Earth. Digging is usually the most convenient method. Fortunately, several digging methods are provided for you on the plane itself, although it pays to go prepared.
It is frequently convenient to dig through the walls of mazes, to make shortcuts between the stairs and minimize the chances that the Wizard of Yendor will show up when you're racing to the upstairs. Similar shortcuts can also make it more feasible to carry sacrifices to altars from adjacent levels.
You can identify undiggable levels by attempting to make a hole by digging. If you can't make more than a pit, it is an undiggable level. This is particularly useful for identifying the deepest level of Gehennom, where the vibrating square is located; this level otherwise looks like another level of Gehennom. If you don't want to move deeper when the level is diggable, you can levitate and zap a wand of digging downward.