Description

Pocket dimensions are small extradimensional spaces created through powerful magic, planar manipulation, or naturally occurring arcane phenomena. Unlike true planes of existence such as the Astral Plane or the Feywild, pocket dimensions are usually artificial spaces formed within or between the boundaries of larger planes.
These spaces are commonly used for magical storage, hidden sanctuaries, secure vaults, transportation, or private demiplanes. Some are temporary and unstable, while others endure for centuries as fully developed miniature worlds.
Well-known examples include Fistandria’s Mansion, the extradimensional spaces created by Mordenkainen’s Magnificent Mansion, and the storage realms contained within Bags of Holding and Portable Holes.

Overview

Pocket dimensions vary enormously in size and complexity. Some consist of little more than a cramped magical container, while others contain fully furnished mansions, ecosystems, or settlements.
Most are created using conjuration magic that bends space beyond the normal laws of the Material Plane. Their interiors are often far larger than their external entrances suggest.
Because they exist partially outside conventional reality, pocket dimensions frequently interact with the Astral Plane, and unstable dimensions can rupture or collapse if damaged.

Physical Properties

Pocket dimensions rarely obey normal physical laws.
Common properties include:

• Interiors vastly larger than their entrances.
• Magical or artificial lighting.
• Altered gravity or orientation.
• Self-sustaining environments.
• Distorted or suspended time flow.
• Limited breathable air in smaller spaces.

Some extradimensional spaces possess fixed layouts, while others reshape themselves according to magical commands or the will of their creator.
More advanced dimensions may contain:

• Permanent magical servants.
• Construct guardians.
• Libraries or laboratories.
• Independent ecosystems.
• Arcane security systems.

Planar Adjacency

Pocket dimensions typically exist adjacent to the Astral Plane, though some are linked to other planes depending upon their creator and purpose.
Extradimensional spaces are often accessed through:

• Magical portals.
• Enchanted containers.
• Doorways or keys.
• Ritual circles.
• Conjuration spells.

Interactions between extradimensional objects can be extremely dangerous. Placing a Bag of Holding inside another extradimensional space, such as a Portable Hole, can create catastrophic planar ruptures connected to the Astral Plane.

Magic on the Plane

Conjuration magic is strongly associated with pocket dimensions, though abjuration and transmutation magic are also common in their construction.
Spells and magical effects associated with pocket dimensions include:

• Mordenkainen’s Magnificent Mansion
• Demiplane
• Rope Trick
• Leomund’s Secret Chest
• Arcane Gate

Magic within pocket dimensions may behave unpredictably if the space is unstable or poorly maintained. Some dimensions suppress teleportation or planar travel entirely as security measures.
Older or abandoned dimensions can develop magical anomalies, lingering enchantments, or dangerous arcane instabilities.

Inhabitants

Pocket dimensions are most commonly inhabited by:

• Wizards and archmages.
• Magical servants and constructs.
• Researchers and scholars.
• Extraplanar entities.
• Smugglers and thieves using hidden storage spaces.

Some dimensions remain empty except for stored objects, while others evolve into permanent residences or hidden strongholds.
Rarely, isolated pocket dimensions develop independent lifeforms or become inhabited by creatures trapped within after magical accidents.

Cosmological Role

Pocket dimensions occupy an unusual role within the cosmology of the multiverse. Though smaller than true planes, they demonstrate the ability of mortal magic to carve stable spaces outside ordinary reality.
They are commonly used for:

• Arcane research.
• Secure storage.
• Planar experimentation.
• Emergency shelter.
• Secret travel routes.
• Prison realms.

Powerful spellcasters sometimes create personal demiplanes as laboratories, sanctuaries, or repositories for dangerous magical knowledge.

Variations by World

Different worlds and magical traditions create pocket dimensions in different ways.
In Faerûn, extradimensional spaces are commonly associated with Netherese magic, powerful wizards, and magical items.
On Eberron, artificers and dragonmarked houses sometimes use advanced arcane engineering to create secure extradimensional vaults.
Within Ravenloft, pocket dimensions may become twisted prison realms shaped by fear, curses, or dark powers.
Some worlds treat extradimensional magic as rare and dangerous, while others incorporate it into everyday magical practice.

Planar Travel

Travelling into a pocket dimension usually requires a specific magical entrance or attuned object.
Common access methods include:

• Entering enchanted containers.
• Opening magical doorways.
• Speaking command words.
• Casting conjuration spells.
• Activating planar keys or sigils.

Pocket dimensions can collapse if their magical structure fails, potentially ejecting occupants into the Astral Plane or trapping them between planes entirely.
Experienced adventurers treat unstable extradimensional spaces with caution, especially when multiple planar effects interact simultaneously.

Locations