Burrowing Rules

By ChronoWaster and CrystalZenaida

Burrowing as per Base 5E

A creature that has a burrowing speed can use that speed to move through sand, earth (dirt), mud, or ice. A creature can't burrow through solid rock worked stone, or any other material unless it has a special trait that allows it to do so.

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Burrowing and Breathing

Unless otherwise stated, a creature must hold their breath as per the Base 5E suffocation rules if they burrow without making a tunnel.

Burrowing and Grappling

For a creature to burrow while carrying or otherwise moving another creature it must leave behind a tunnel as part of its burrowing movement. This tunnel must be large enough to fit the burrower and the grappled creature.

Moving and Digging for Creatures without a Burrow Speed

Tunnels function as difficult terrain for any creature without a burrow speed.
If a tunnel is collapsed or blocked off, a creature without a burrow speed can spend an action to dig up to an amount of feet equal to:

5 x Half their Strength (Athletics) modifier (Rounded down and minimum 1)

If a creature has digging equipment like a shovel or a pickaxe, they can spend an action to dig up to an amount of feet equal to:

5 x their Strength (Athletics) modifier (minimum 1)

This digging action is still limited by difficult terrain and the creature’s remaining movement.
This digging action is also intended only for escaping from/chasing through a creature’s burrow path, and is only possible because of the burrowing creature’s disturbance of the ground.
A tunnel made by a creature without a tunneling trait collapses in 5 rounds from the point of creation.
When a tunnel is collapsed, a conscious creature inside the tunnel can hold its breath as per the Base 5E suffocation rules.

Attacking a Burrowed Creature

A creature that burrows 5 feet underground can still be targeted by melee attacks, but the burrow creature has three-quarters cover.
Unless otherwise stated or if a reasonable tunnel is present, ranged attacks and melee attacks past 5 feet can not be made against a burrowed creature.

Attacking as a Burrowed Creature

If you are burrowed 5 feet underground and make a melee attack on a creature above ground, the creature above ground has three-quarters cover.
Unless otherwise stated or if a reasonable tunnel is present, ranged attacks and melee attacks past 5 feet can not be made against a hostile creature if you are burrowed.

Area of Effect and Burrowing

A burrowing creature can still be affected by area of effect abilities and spells whose origins are above the ground while in range and that do not rely on sight, though it results in half damage unless the damage type is bludgeoning, force, or thunder. However, area of effect abilities and spells originating from below the earth can not affect those above ground unless otherwise stated. (Earthquake for example)

Detecting a Burrowed Creature

While burrowing provides cover it is difficult for anything but the smallest creatures to burrow quickly without causing disturbances in the ground above (Vibrations, mounds, ect). If a burrowed creature is not stealthed, creatures will be able to tell the general location of it with either a passive or active Wisdom (Perception) check DC equal to:

8 + 2 for every 5 feet underground

This DC is increased by 2 for each size category below medium, and reduced by 2 for each size category above medium. A creature without tremorsense can not detect a burrowed creature if it is 60 feet or more below the earth.

Types of Burrowing:

Burrowing (Default): The creature digs through the earth leaving loosely packed material behind it. Mildly disruptive to the earth.
Tunneling (Trait): The creature tunnels through the earth and leaves a tunnel behind it. Very disruptive to the earth, and sized similarly to the creature making the tunnel.
Earth Glide (Trait): The creature melds into the earth and moves through it. Does not disturb the earth.