The underground area from the original Pokémon Diamond and Pearl has received such a big upgrade it’s known as the “Grand” Underground in Pokémon Brilliant Diamond and Shining Pearl. There’s lots to do and see, so the following resources should make your spelunking a little easier. Within the Grand Underground, you’ll be able to dig for valuable items and hunt for rare Pokémon
Unlocking the Grand Underground
It doesn’t take long to unlock the ability to visit the Grand Underground; once you reach Eterna City, you can obtain the Explorer Kit required to access it from the Underground Man in the house next to the Pokémon Center. You will be transported to the Grand Underground to explore for yourself right after obtaining it.
Map of Pokémon Hideaways in the Grand Underground
The map above was originally created by Japanese fansite Yakkun and translated for English audiences by us. Cities listed as entry points for specific parts of the underground include some surrounding routes.
Expanding the variety of Pokémon in Hideaways
By completing certain objectives, the varieties of Pokémon that will spawn in each Hideaway will increase. The most substantial increase comes in conjunction with receiving the National Pokédex, but here are the full list of events which will upgrade your Hideaway populations:
- Gain access to Defog in Pokétch
- Gain access to Strength in Pokétch
- Earn Icicle Badge by defeating the Snowpoint City Gym
- Gain access to Waterfall in Pokétch
- Obtain the National Pokédex upgrade
Levels of Pokémon found in Hideaways
The level of Pokémon encountered in Hideaways will vary based on your progress in the Sinnoh Pokémon League:
- One badge: Levels 16-20
- Two badges: Levels 25-29
- Three badges: Levels 29-33
- Four badges: Levels 33-27
- Five badges: Levels 36-40
- Six badges: Levels 39-43
- Seven badges: Levels 42-46
- Eight badges: Levels 50-55
- Elite 4 defeated: Levels 58-63
Annotated map of the Grand Underground NPC locations
During your adventures in the Grand Underground, there are some very special NPCs that you may want to locate. You can expand your base, trade spheres with vendor NPCs that are looking for different sizes of spheres and heal your Pokémon. The map below uses symbols to display where you can expand your base, the location of large sphere vendors, the location of small sphere vendors and the location of medics, along with an overall look at the Grand Underground itself.
The map above is based on one originally created by nakfu1 of Reddit!
How to create a Secret Base
To create a Secret Base in Pokémon Brilliant Diamond or Shining Pearl, you’ll need an item called a Digger Drill. These are stored in the ‘Treasures’ pocket in your bag and one can be received for free after talking to the Underground Man again after he gives you the Explorer Kit, although you must dig up some items to satisfy his request (if you already have, you can immediately talk to him again). More drills can be bought from NPCs, refer to the map above.
In order to create your Secret Base, choose a location where you’d like to place the entrance, then simply press ‘A’ when facing the wall. It will ask if you want to use the drill (it cannot be used from the bag). Then you’ve created a Secret Base, which you’re free to decorate with encounter-affecting statues!
Diglett and Dugtrio appearances in the Grand Underground
You may see Diglett and Dugtrio appear, but scurry away before you can reach them. They will leave energy for you to pick up, 1 if it was a Diglett, 3 if it was a Dugtrio, and there are special bonuses if you collect 40 energy in one play session. Your chances of finding a Shiny Pokémon become 1 in 2048, essentially doubling from the normal rate. You are also more likely to find a Gorgeous Box while digging.