The Grand Underground in Pokémon Brilliant Diamond and Shining Pearl is the reworked version of the Underground network of the Sinnoh region from the original games.
Within the Grand Underground, you'll find Pokémon Hideaways, which contain Pokémon from other regions, such as Houndoom. You can also build a Secret Base and fill it with statues that have an effect on the Pokémon Hideaways.
You can also find items such as fossils and evolution stones by digging in the Grand Underground - as long as you know how to dig.
First, however, you need to know how to get to the Grand Underground and understand how the Grand Underground map works.
On this page:
- How to unlock Grand Underground in Pokémon Brilliant Diamond and Shining Pearl
- Grand Underground map in Pokémon Brilliant Diamond and Shining Pearl
- Pokémon in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
- Statues and Secret Bases in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
- How to dig and digging rewards list in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
- Diglett and Dugtrio in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
- Vendors and Spheres in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl
- Multiplayer for the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl
How to unlock Grand Underground in Pokémon Brilliant Diamond and Shining Pearl
To unlock the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl, you must first reach Eterna City. This is the third major city you'll visit in the game, containing the second Gym, and takes roughly five hours to reach.
The Grand Underground is unlockable the moment you set foot in Eterna City - simply visit the house next to the Pokémon Centre and talk to the old man inside.
He'll give you the Explorer Kit, which can be found in the Key Items pocket of your bag, and a short tutorial on how the Grand Underground works. This includes entering and exiting the Grand Underground and building a Secret Base, which he'll give you a Digging Drill for.
Completing this tutorial is not necessary and you can simply focus on enjoying the Grand Underground the moment you have the Explorer Kit. If, however, you do wish to complete the tutorial, return to the old man after you complete each of the tasks until he doesn't have any left you.
Grand Underground map in Pokémon Brilliant Diamond and Shining Pearl
The Grand Underground can be accessed from the majority of the Sinnoh region in Pokémon Brilliant Diamond and Shining Pearl. Just make sure you're not in a house or cave, because access will be barred!
To find your location within the Grand Underground, open your map - the section you're currently in will be glowing green and you'll be represented by a red dot. Feel free to wander as far as you like, because you'll always return to the spot where you entered the Grand Underground.
On the Grand Underground map, you'll notice squares containing question marks - these are the Pokémon Hideaways. These question marks will be filled in the first time you visit a Pokémon Hideaway, helping you remember which biome is where.
Below you can see the full Grand Underground map:
As you can see, the Grand Underground is designed to roughly match the map of aboveground Sinnoh. This means, to access certain sections, you must enter the Grand Underground from specific parts of the Sinnoh region.
Below you can find the locations you have to be in to reach the specific parts of the Grand Underground - the unnumbered section can be entered from any location, such as Eterna City, which isn't listed below.
- Twinleaf Town, Canalave City, Ramanas Park and their adjoining routes
- Full Moon Island, Snowpoint City and their adjoining routes
- Celestic Town
- Sunnyshore City
- Battle Zone
Pokémon in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
Pokémon Hideaways are the caves and caverns of the Grand Underground which you'll be visiting often in Pokémon Brilliant Diamond and Shining Pearl, because they contain Pokémon, including ones which don't appear in the Sinnoh Pokédex. This means that you can catch Pokémon like Houndoom and Absol before unlocking the National Pokédex during the post-game.
More Pokémon will appear throughout the Pokémon Hideaways as you progress through the main campaign and when you unlock the National Pokédex, so you should make regular visits to see if you encounter any new creatures. Some of these Pokémon may not appear on the surface world of Sinnoh.
If you'd like to see the full list of Pokémon you can encounter in the Grand Underground, then visit our dedicated Pokémon Hideaways guide.
Some of the Pokémon Hideaways also contain important items like evolution stones and TMs. Use them wisely though, because you can only collect these items once!
Statues and Secret Bases in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
Just like in the original games, Pokémon Brilliant Diamond and Shining Pearl allow you to create Secret Bases in the Grand Underground.
You need a Digger Drill to create a Secret Base - one can be earned from the old man who gives the Grand Underground tutorial in Eterna City and certain vendors in the Grand Underground will have them for sale.
To use a Digger Drill, simply walk up to a wall where you'd like to build a Secret Base and you'll be given the option to build one. As long as you have a Digger Drill in your bag, you'll be able to move your Secret Base whenever you like. Thankfully, you won't have to rearrange your statues every time you move your Secret Base.
Unlike the originals, however, you can only place statues and pedestals in your Secret Base.
These statues increase the chance of certain Pokémon types appearing in the Pokémon Hideaways with the specific type being based upon the statue's own typing; if you place an Alakazam Statue in your base, for example, the chance of encountering psychic Pokémon will be increased.
This boost is based upon the type you've placed the most statues for, so, if you've placed mostly fire and one water-type statue, then the boost you receive will be for fire-type Pokémon. If you've placed any multi-type statues, then the boost they give will default to the most present typing.
You can check the dominant boost of your statues by interacting with the crystal ball inside your Secret Base.
There are three types of statues for you to find - Standard, Color and Legendary.
Standard and Color statues are both found by digging in the Grand Underground - Standard statues come from Pretty Boxes and Color from Gorgeous Boxes. Legendary Statues are earned by catching specific legendary Pokémon in Ramanas Park, which is accessible after you've defeated the Elite Four and unlocked the National Pokédex.
Color statues will give a higher boost than Standard and Legendary gives the highest type bonus of all. The size of the statue also matters, with bigger statutes providing higher boosts.
Statues can be placed on pedestals, but doing so won't provide you any additional boosts. It will, however, make your Secret Base look a little more organised! To use a pedestal, simply, when organising your statues, select the statue you wish to place on a pedestal and then choose the pedestal option to see which ones are available for this object.
You can place up to 18 statues at one time - as long as you have the room for them! Thankfully, it's possible to expand your base two times by finding the right vendor in the Grand Underground and exchanging a heavy amount of spheres.
Your Secret Base can be expanded two times, costing the following amounts:
- 60 Red Sphere S
- 60 Blue Sphere S
- 60 Green Sphere S
- 30 Prism Sphere S
- 30 Pale Sphere S
- 40 Red Sphere L
- 40 Blue Sphere L
- 40 Green Sphere L
- 20 Prism Sphere L
- 20 Pale Sphere L
How to dig and digging rewards list in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
Digging in the Grand Underground allows you to collect a variety of items which are either rare or don't appear in the aboveground world of Pokémon Brilliant Diamond and Shining Pearl.
To do some digging, you must first find a digging spot, which appear as yellow dots on the Grand Underground minimap. Once you're near one of these dots, press A when standing in front of the wall until you find the digging spot and have the option to start the digging minigame.
At the beginning of each digging session, you'll be informed how many items are hidden in the section of wall you're destroying. The aim is to find all of these items before the wall collapses, but, even if you don't find all of the items, you will always keep those you successfully uncover.
The crack which appears at the top of the screen will help you keep track of how close the wall is to collapsing, with the minigame ending when the crack reaches the left side of the screen. To find the items you need to dig through different layers of dirt until you uncover them.
Be careful though, there are also sections of metal hidden in the wall and they will also cause wall damage if hit.
When it comes to the digging itself, you have two tools at your disposal - the hammer and the pic.
The hammer is the most effective tool, affecting the layers of nine tiles, but at the cost of causing more damage to the wall. The pic, meanwhile, causes less wall damage, but only affects four titles.
We recommend using the hammer to locate items and then the pic to carefully excavate them. To fully excavate an item, you need to remove all of the dirt surrounding it, so you can see it properly.
If you manage to successfully find all of the items before the wall collapses, then the minigame will automatically end. Yet, if the wall does collapse, you'll only receive the items you managed to fully find.
Digging can reward you with statues and the items listed below:
- Fire Stone
- Leaf Stone
- Moon Stone
- Oval Stone
- Sun Stone
- Thunder Stone
- Water Stone
- Armor Fossil - exclusive to Shining Pearl
- Claw Fossil - unlocked after catching or defeating either Dialga or Palkia
- Dome Fossil - unlocked after catching or defeating either Dialga or Palkia
- Helix Fossil - unlocked after catching or defeating either Dialga or Palkia
- Odd Keystone
- Old Amber - unlocked after catching or defeating either Dialga or Palkia
- Root Fossil - unlocked after catching or defeating either Dialga or Palkia
- Skull Fossil - exclusive to Brilliant Diamond
- Heart Scale
- Max Revive
- Rare Bone
- Star Piece
- Blue Shard
- Green Shard
- Red Shard
- Yellow Shard
Shards for Ramanas Park:
- Mysterious Shard S - unlocked after catching or defeating either Dialga or Palkia
- Mysterious Shard L - unlocked after catching or defeating either Dialga or Palkia
- Blue Sphere S
- Blue Sphere L
- Green Sphere S
- Green Sphere L
- Pale Sphere S
- Pale Sphere L
- Prism Sphere S
- Prism Sphere L
- Red Sphere S
- Red Sphere L
Stat and move boosting items:
- Damp Rock
- Draco Plate
- Dread Plate
- Earth Plate
- Flame Plate
- Fist Plate
- Hard Stone
- Heat Rock
- Icicle Plate
- Icy Rock
- Insect Plate
- Iron Ball
- Iron Plate
- Light Clay
- Meadow Plate
- Mind Plate
- Pixie Plate
- Sky Plate
- Smooth Rock
- Splash Plate
- Spooky Plate
- Stone Plate
- Toxic Plate
- Zap Plate
Diglett and Dugtrio in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl explained
When venturing through the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl, you might see a Diglett or Dugtrio at a junction or corner.
These Pokémon will vanish before you can reach them, but they will leave behind a small amount of energy for you to collect - 1 for Diglett and 3 for Dugtrio.
You'll be able to keep track of how much energy you've collected by looking at the metre beneath the Grand Underground minimap in the top left-hand corner. Once you've collected 40 pieces of energy in one visit to the Underground, the chances of you encountering Shiny Pokémon in the Pokémon Hideaways will increase.
It's important to remember, however, that this energy metre will reset every time you leave the Grand Underground, so, no matter your progress, you'll have to start from zero when you re-enter the Underground.
It’s time to revisit Sinnoh! Our now complete Diamond and Pearl walkthrough to the main story is where to start. Your journey begins with selecting your starter Pokémon near Twinleaf Town, before visiting Sandgem Town and Jubilife City. To become a Pokémon Master, you need to defeat the Gym Leaders in Oreburgh City, Eterna City, Veilstone City, Pastoria City and Hearthome City, along with three others.
Aside from badges, you’ll want to grab Mystery Gift codes, complete the Sinnoh Pokédex by using Honey Trees, visiting the Great Marsh and the Pokémon Hideaways in the Grand Underground. Take the time to catch Gible, Spiritomb andDrifloon! Finally, you can now catch Arceus.
Vendors and Spheres in the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl
You'll encounter a variety of vendors when exploring the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl who, in exchange for Spheres, will offer you a variety of services.
Spheres are the currency of the Grand Underground and can be obtained by digging, exchanging specific items or exchanging a specific type of Sphere for another with vendors. There are two different Sphere sizes - small and large - and five different types of Sphere: Blue, Green, Pale, Prism and Red.
Different vendors offer different services - some will exchange items, such as fossils or items you obtain through digging, others offer to expand your Secret Base and some sell items like TMs, pedestals for your statues and different types of Spheres.
Their stock will change on a daily basis, so, if they don't have what you need for sale, try visiting on a different day. This change also includes which spheres you can use to purchase items - the Digger Drill may cost 10 Red Sphere S one day and 10 Blue Sphere S the next.
You may also encounter people who will heal your Pokémon, which is very useful if you're catching Pokémon in the Pokémon Hideaways. There are also NPCs who will offer you advice and insight about the Grand Underground.
Multiplayer for the Grand Underground of Pokémon Brilliant Diamond and Shining Pearl
If you don't want to explore the Grand Underground alone, you can utilise Pokémon Brilliant Diamond and Shining Pearl's multiplayer capabilities.
Every time you enter the Grand Underground, you'll be given the option to play alone, through local communication or using the Internet.
Using local communication will allow you to join any players who are in your vicinity, but selecting the Internet will allow you to play alongside people from around the world. You will need a Nintendo Switch Online membership to visit the Grand Underground using the Internet.
The location of other players will be marked by blue dots on your Grand Underground map, moving when they do, and, if there are any Secret Bases in the section of tunnels you're currently in, they too will appear as blue dots.
You'll be able to communicate with other players using a selection of icons and visit other player's Secret Bases if you so choose. Players will also share the Diglett energy progress bar, which makes it easier to find shiny Pokémon in the Grand Underground.
It's also possible to dig alongside other players and, when someone starts digging near you, you'll be able to see sets of sparkles either side of them, which will notify you of the available digging spots.
Finally, the game will notify you when people enter or leave the Grand Underground whether you're playing locally or through the Internet.
Have fun in the Grand Underground!