Grand Underground guide for Pokémon Brilliant Diamond & Shining Pearl

The Grand Underground has made a triumphant return in Pokémon Brilliant Diamond and Shining Pearl on Nintendo Switch. This feature can be accessed early on in the adventure, just before the second gym battle, so it’s worth grabbing the Explorer’s Kit as soon as possible. This iteration of the Grand Underground has received a number of changes, such as the addition of Pokémon hideaways and increased shiny odds. So to help, this guide will teach you everything you need to know about the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl.

How to unlock the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl

BDSP Grand Underground explorer's kit location

After dealing with the Team Galactic shenanigans in Floraoma Town, you will eventually traverse Eterna Forest before setting foot into Eterna City. Upon your arrival, simply enter the house next to the Pokémon Center and talk to the old man, and you will receive the Explorer’s Kit. This will then allow you to enter the Grand Underground any time you want by simply using the Explorer’s Kit in your inventory.

Encounter rare Pokémon in hideaways

Grand Underground guide for Pokémon Brilliant Diamond & Shining Pearl Hideaway in BDSP

A brand new feature has been added to The Grand Underground in Brilliant Diamond and Shining Pearl called Pokémon hideaways. While exploring the underground, you will notice titles with a big question mark on them — this signals that you are about to enter a Pokémon hideaway.

Grand Underground guide for Pokémon Brilliant Diamond & Shining Pearl BDSP Golbat in hideaway fight

Be sure to take advantage of these caverns, as you can find rare Pokémon in them, such as the elusive Munchlax. Additionally, you may have an increased chance of finding a shiny Pokémon in the hideaways, but this is still under investigation by the community.

Go digging for treasure!

BDSP grand underground wall dig

On the Grand Underground map, you will notice these orange sparkles on the map screen indicating that some items can be obtained. Pressing A while standing next to one of these visual clues will allow you to dig for treasure, enabling you to receive fossils, held items, and more. If you’re struggling to locate the exact position that you need to be in, press R to activate a radar, which will give you an extra visual indication of where to stand.

BDSP underground digging

There are two tools to help you claim your goodies, the Sledgehammer and Pickaxe, but you have a limited number of hits before it collapses. This is visible to you at the top of the screen with the crack, which will grow bigger the more you try to dig. Don’t go over the top with it though, as you may miss out on some important items. For example, in Brilliant Diamond, you can find the Skull Fossil to receive a Cranidos, while in Shining Pearl, you have a chance of obtaining the Armor Fossil, allowing you to get your hands on Shieldon.

Grand Underground digging for items

How to create a Secret Base in the Grand Underground

bdsp underground secret bases

If you played Pokémon Ruby and Sapphire or their remakes, Omega Ruby and Alpha Sapphire, you may be familiar with Secret Bases. In Pokémon Brilliant Diamond and Shining Pearl, the Grand Underground is home to Secret Bases, and this guide will show you how to create one. To get started with Secret Bases, you need to acquire a Digging Drill — these can be obtained from vendors in the underground, so make sure you talk to people when you see them. However, you can obtain one for free if you speak to the Underground Man after exploring the underground for a bit.

Grand Underground guide for Pokémon Brilliant Diamond & Shining Pearl BDSP Alakazam Statue

Once you’ve decided on a spot for your Secret Base, use the Digging Drill to set it up. However, if you decide later that you want to move it, purchase another Digging Drill to move it to a different location. To decorate your secret base, mine items throughout the various underground tunnels to receive cosmetics such as statues, pedestals, and more. Placing statues for specific Pokémon will also manipulate their spawn rate in the Underground’s hideaways.

Diglett Dig in this minigame

Diglett underground mini-game BDSP

During your Grand Underground escapades, take a look at the top left corner of the screen to notice a meter that goes up to a maximum of 40. This is what is called the Diglett mini-game, which has some interesting rewards for maxing out the bar. While exploring, you may encounter a Diglett or Dugtrio, and if you interact with them, they run away and leave behind energy particles. The former rewards the player with 1 point, while the latter hands over 3 instead.

Once you reach 40, for four minutes, the shiny chances in Pokémon hideaways will become 1 in 2048 instead of the usual 1 in 4096. Also, you will have a greater chance of finding rarer statues within this time period as well. With that in mind, it might be worth going out of your way to encounter the iconic Ground types.

This guide has offered everything you need to know about the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl. For tips beyond the Grand Underground, check out our other Pokémon Brilliant Diamond and Shining Pearl guide content:

Jaimie Ditchfield
Freelance Writer. Work seen on Zelda Universe and BackToTheGaming. Studied Games Journalism and PR for three years, and is relentless at spreading his love for The Legend of Zelda: Majora's Mask. The chances are you'll also hear him scream Persona.

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