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Pokémon: Brilliant Diamond & Shining Pearl

How to Access the Underground

By
Vincent Lau

This page outlines how to enter the Grand Underground.

The Grand Underground is a massive labyrinth located deep underneath Sinnoh. In the original Diamond and Pearl, it was simply known as the “Underground”. Here, you can freely explore, dig up useful items, set up a base or even find rare Pokémon.

To access the Grand Underground, you must first obtain the Explorer Kit.

Where is the Explorer Kit?

(1 of 2) When you use the Explorer Kit, a hole will appear underneath you.

When you use the Explorer Kit, a hole will appear underneath you. (left), You’ll then fall down into the corresponding section of the Grand Underground. (right)

You can get the Explorer Kit from Eterna City, via the house to the right of the Pokémon Center. The Explorer Kit will be stored in the Key Items section of your bag. Using the kit, you can instantly travel to the Grand Underground from almost anywhere.

The location where you use the kit will determine where you begin in the Grand Underground. However, the reverse is not true; using the Explorer Kit again will always return you to your original location, no matter where in the Grand Underground you are.

Underground Activities

While in the Grand Underground, you can partake in the following:

Pokémon Hideaways

(1 of 2) Hideaways are small biomes with a wide variety of Pokémon!

Hideaways are small biomes with a wide variety of Pokémon! (left), You can enter battles by touching wild Pokémon. (right)

Dotted around are various large rooms (indicated by a question mark on the map) that contain miniature environments, such as volcanic landscapes. These are called Pokémon Hideaways.

Unlike your adventures above ground, you can physically see the wild Pokémon, similar to Pokémon Sword and Shield. Also, the Pokémon that you can encounter include those not normally found in the Sinnoh region.

Dig for Treasure

(1 of 2) Use the Dowsing Machine app to reveal the walls you can dig.

Use the Dowsing Machine app to reveal the walls you can dig. (left), Diamond and Pearl fans may recognize this screen! (right)

Certain walls can be inspected. A puzzle screen will appear, where you can use a sledgehammer and pickax to dig away at the wall, potentially revealing valuable treasure. However, there’s a limit to how many times you can dig, before the wall collapses and you’re forced to leave.

  • The Sledgehammer clears away a wider area of rocks, but will cause the wall to collapse more.
  • Meanwhile, the Pickax works on a smaller area, but will cause less damage to the wall.

It’s a good idea to start with the Sledgehammer, then swap over to the Pickax to focus on a specific area. You can swap tools by pressing the R button or tapping the touch screen.

To obtain a treasure, you must fully uncover it–in other words, it’s completely visible, with no rocks obscuring it. Once you’ve recovered all the treasure or the wall reaches its limit, you’ll receive all the treasure you recovered.

Secret Base

(1 of 2) This looks like a good spot to make a base.

This looks like a good spot to make a base. (left), You can fill your base with statues of various sizes. (right)

You can use the Digger Drill on a wall to create an entrance to your own Secret Base. Inside your base, you can place Pokémon statues, which can alter the species of Pokémon that appear in Hideaways.

Multiplayer

It’s possible to explore the Grand Underground with other players via Local or Online communications. Each player will need their own Nintendo Switch and copy of Brilliant Diamond or Shining Pearl. Also, for Online play, each player must have an active Nintendo Switch Online subscription.

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Guide Information

  • Publisher
    Pokemon Company International
  • Platforms
    Switch
  • Genre
    RPG
  • Guide Release
    29 October 2021
  • Last Updated
    3 December 2021
    Version History
  • Guide Author

Share this free guide:

This strategy guide for Pokémon Brilliant Diamond & Shining Pearl contains all the information Pokémon trainers will need to complete the game and catch every single Pokémon!

In this remake of the classic Pokémon Diamond & Pearl, you’ll journey through the mystical Sinnoh region to become a Pokémon master. Along the way, you’ll confront the scheming Team Galactic and witness the awesome power of the Legendary Dialga or Palkia.

The finished version of our guide will contain:

  • Tips for Adventuring in Sinnoh.
  • Tips for Pokémon battling.
  • An introduction to the Grand Underground.
  • An introduction to Super Contest Shows.
  • A complete walkthrough of the main story and postgame.
  • Strategies for defeating the Gym Leaders and Elite Four.
  • Wild Pokémon and item locations for each route and dungeon.
  • A full breakdown of the Grand Underground.
    – All the Pokémon that inhabit the Hideways.
    – Information for all the treasure you can dig up.
  • A full guide for Super Contest Shows.
    – How to cook the best quality Poffins.
  • Explanation of advanced mechanics, such as IVs and EVs.
  • How to breed Pokémon.
  • A detailed Sinnoh region Pokédex.

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