# Tunneling monster
A tunneling monster is a monster with the ability to bore tunnels through the normally solid dungeon. Tunneling monsters can tunnel through rock and closed doors, and chop down trees.
Some monsters can only tunnel through rock while wielding a pick-axe or dwarvish mattock, and through trees while wielding an axe or battle-axe. Both picks and axes suffice for doors.
Note that any monster that can tunnel at all can go through both rock and wood. Rock moles can eat trees and woodchucks can apparently chuck rock.
No monster can tunnel through the specially designated undiggable walls in some special levels.
If you polymorph into a naturally tunneling monster you will gain the ability to tunnel without a pick. You will still be able to use a pick, provided your new form has hands and is strong enough to carry it. Rock moles, for instance, generally cannot even lift a pick-axe. Your digging is handled separately however, even while in polyform.

Contents

1 Effects

1.1 Wall
1.2 Solid rock
1.3 Tree
1.4 Door

2 Monsters capable of tunneling

2.1 Without a pick-axe or axe
2.2 With a pick-axe or axe

3 Messages
4 Technical details
5 See also
6 References

Effects
Wall
When a monster tunnels through a rock wall, there is a 1⁄5 chance of producing the message "You hear crashing rock."[1]

Solid rock
When a monster tunnels through solid rock (the blank areas surrounding most of the dungeon), there is a 1⁄3 chance of some waste being produced. 1⁄4 of the time this waste will be a boulder, the rest of the time it will be a single rock. No message is produced.[2][3]

Tree
When a monster tunnels through a tree, there is a 1⁄3 chance of a random piece of fruit being produced, chosen from apple, orange, pear, banana, and eucalyptus leaf. No message is produced.[4]

Door
When a monster tunnels through a closed door, there is a 1⁄3 chance of producing the message "You feel an unexpected draft."[5]

Monsters capable of tunneling
Without a pick-axe or axe
r&nbsp;rock mole
r&nbsp;woodchuck
U&nbsp;umber hulk
With a pick-axe or axe
Dwarves:
h&nbsp;dwarf
h&nbsp;dwarf lord
h&nbsp;dwarf king
Archeologist related:
@&nbsp;student
@&nbsp;archeologist
@&nbsp;Lord Carnarvon
Messages
You hear crashing rock.
Produced 1⁄5 of the time when a monster tunnels through a rock wall.
You feel an unexpected draft.
Produced 1⁄3 of the time when a monster tunnels through a door.

<monster> digs in.
Produced when a pet umber hulk, woodchuck, or rock mole eats something off the ground in your sight. This YAFM replaces the ordinary pet eating message.[6]
Technical details
Monsters that can tunnel have the M1_TUNNEL monster attribute. Monsters that require picks and axes also have the M1_NEEDPICK monster attribute in addition to M1_TUNNEL. No monster in vanilla NetHack has M1_NEEDPICK but not M1_TUNNEL.

See also
m_move in monmove.c – decides when and if monsters can and will tunnel.
mdig_tunnel in dig.c – performs the tunneling. Called by m_move.
References

↑ dig.c in NetHack 3.6.0, line 1286

↑ dig.c in NetHack 3.6.0, line 1244

↑ dig.c in NetHack 3.6.0, line 1305

↑ dig.c in NetHack 3.6.0, line 1301

↑ dig.c in NetHack 3.6.0, line 1250

↑ dogmove.c in NetHack 3.6.0, line 271

This page may need to be updated for the current version of NetHack.
It may contain text specific to NetHack 3.6.0. Information on this page may be out of date.
Editors: After reviewing this page and making necessary edits, please change the {{nethack-360}} tag to the current version's tag or {{noversion}} as appropriate.

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