View source for Grand Underground

{{Infobox location
|image=Grand Underground map BDSP.png
|type=cave
|location_name=Grand Underground
|japanese_name={{tt|地下大洞窟|ちかだいどうくつ}}
|translated_name=Grand Underground Cave
|location=Beneath [[Sinnoh]]
|region=Sinnoh
|generation={{gen|VIII}}
|map=sinnoh.png
}}
The '''Grand Underground''' (Japanese: '''{{tt|地下大洞窟|ちかだいどうくつ}}''' ''Grand Underground Cave'') is an area in {{g|Brilliant Diamond and Shining Pearl}} found beneath the entire [[Sinnoh]] [[region]]. Players can travel to the Grand Underground using an [[Explorer Kit]], found in [[Eterna City]].

It takes the place of [[the Underground]] from {{game2|Diamond|Pearl|Platinum}}.

==Changes from Diamond and Pearl==
[[File:Grand Underground BDSP.png|thumb|300px|right|{{ga|Lucas}} and {{ga|Dawn}} in the Grand Underground]]

* The map now conforms to the shape of the Sinnoh landmass instead of a large square layout. Notably, it excludes [[Iron Island]], [[Fullmoon Island]], and [[Route 223]] onwards.
* The map is still split into six disjoint areas like the original Underground, but the sizes and locations of the six areas do not match those of the original Underground.
* Areas now include Pokémon Hideaways, and each area now corresponds to a different aesthetic environment.
** At least 2 areas include surfable water. These hideaways are the Swampy Cave and the Lakeside Cave.
* The digging minigame returns following closely to its original incarnation with the exception of digging up Pokémon statues, which come from Stone Boxes. There are at least two kinds of Stone Boxes, the common Pretty Stone Boxes and the rare Gorgeous Stone Boxes. Statues acquired from Pretty Stone Boxes are made of normal stone, while statues from Gorgeous Stone Boxes are made of jade. There is a box for each [[type]].
** These statues may seemingly depict [[Shiny Pokémon]], due to the Pokémon's names having the shiny symbol next to it. It is unknown if this has any effects other than aesthetics.
* [[Secret Base]]s return and are created using a [[Digger Drill]] as before.
** Bases can only be decorated with statues and pedestals to place them on. Adding more of a specific [[type]] will slightly increase the chances of that type appearing in hideaways. This "Statue Effect" is indicated by the orb place next to the entrance of the player's base. The flag stealing mechanic has also been removed.
* [[Goods]] and [[Traps]], with the sole exception of the Digger Drill, have been removed.
* Spheres no longer have a numerical size and are instead categorized as Small or Large. They can no longer be buried either.
* Instead of goods or traps, merchants (who appear as [[Hiker]]s) in the Grand Underground can exchange treasures and for spheres. Spheres can now be exchanged for pedestals, items, and TMs.
* The radar is now triggered by pressing [R] and searches the area around the players location.
* The Grand Underground supports online communications, compared to the original games which only supported local communications.
* [[Diglett]] and [[Dugtrio]] will occasionally pop out and leave pink sparkles that give 1 and 3 points respectively. Accumulating 40 of these points causes "something good to happen" and new digging spots with green sparkles appear that do not need radar to be found. All Stone Boxes found during this will be Gorgeous Stone Boxes. A whistle is heard when this period begins and once more when it ends.
**Leaving the Grand Underground resets the gauge, even if the player return to the same section immediately after.

==Additional Information==
*Merchants asking for small spheres allow the player to purchase additional [[Digger Drill]]s to make a base with. The player cannot have more than one base at a time, even if they're made in different sections of the Underground. Trying to make an additional one will delete the previous base made.
*Merchants may give the player the option to expand their base. Doing this requires 60 small Red Spheres, Green Spheres, and Blue Spheres each, along with 30 small Pale Spheres and Prism Spheres.
*Some [[Hiker]]s found in the Grand Underground allow the player to rest, acting as a [[Pokémon Center]]. 
*If the player runs out of digging spots, more will appear once the player enters and exits a Hideaway.

===Pokémon Hideaways===
'''Pokémon Hideaways''' (Japanese: '''ポケモンの{{tt|隠|かく}}れ{{tt|家|が}}''' ''Pokémon Hideaway'') are new places where [[wild Pokémon]] can be encountered. Unlike the main overworld, these areas feature [[symbol encounter]]s. Some Pokémon available in the game can only be found in Hideaways. All Pokémon in the Hideaways will have at least one [[Egg Move]] if applicable, and earning more [[Badge]]s, becoming [[Champion]], and obtaining the [[National Pokédex]] will increase the strength and variety of Pokémon found in the Hideaways.

Each of the six areas appear to contain one large Hideaway along with multiple much smaller Hideaways, with the exception of the largest area, which has two large Hideaways.

The Grand Underground unlocks some Egg Moves that are otherwise unobtainable, e.g. {{m|Aura Sphere}} on {{p|Squirtle}}.

==In other languages==
{{langtable|color={{locationcolor/light|cave}}|bordercolor={{locationcolor/dark|cave}}
|zh_yue=地下大洞窟 ''{{tt|Deihhah Daaihduhngfāt|Grand Underground Cave}}''
|zh_cmn=地下大洞窟 ''{{tt|Dìxià Dàdòngkū|Grand Underground Cave}}''
|fr=Grands Souterrains
|de=Untergrundhöhlen
|it=Grandi Sotterranei
|ko=지하대동굴 ''{{tt|Jiha Daedonggul|Grand Underground Cave}}''
|ru=Великое подземелье ''Velikoye podzemel'ye''
|es=Grutas del Subsuelo
}}

''Pokémon Hideaway''
{{langtable|color={{locationcolor/light|grass}}|bordercolor={{locationcolor/dark|grass}}
|zh_yue=寶可夢秘巢 ''{{tt|Pokémon Beichàauh|Pokémon Den}}''
|zh_cmn=寶可夢秘巢 / 宝可梦秘巢 ''{{tt|Pokémon Mìcháo|Pokémon Den}}''
|fr=Cachette de Pokémon
|de=Pokémon-Unterschlupf
|it=Rifugio di Pokémon
|ko=포켓몬 은신처 ''{{tt|Pokémon Eunsincheo|Pokémon Hideaway}}''
|ru=Укрытие Покемонов ''Ukrytiye Pokémonov''
|es=Guarida Pokémon
}}

{{Sinnoh}}<br/>
{{Project Locations notice}}

[[Category:Sinnoh locations]]
[[Category:Brilliant Diamond and Shining Pearl locations]]
[[Category:Caves]]

[[es:Grutas del Subsuelo]]
[[it:Grandi Sotterranei]]
[[ja:地下大洞窟]]
[[zh:地下大洞窟]]