The Grand Underground is the biggest new feature of Brilliant Diamond and Shining Pearl. It replaces the Underground of Diamond and Pearl and keeps its essentials (digging, Secret Bases, multiplayer), but adds hideaways where Pokémon you can’t find on the surface live. This page explains how to get in, how to dig efficiently, what statues are for and how to make the most of the hideaways.
Getting into the Grand Underground
You get in with the Explorer Kit, handed out early in the adventure by the Underground Man, who lives in Eterna City next to the Pokémon Center. Once the Explorer Kit is in your bag, you can go underground almost anywhere on the surface. The network covers all of Sinnoh, but it isn’t one continuous space: some sections are separate, and you sometimes have to come back up to the surface to get from one area to another.
| Area | Surface access |
|---|---|
| Northwest | Snowpoint City |
| Northeast | Battle Zone |
| Southwest | Ramanas Park, Oreburgh City |
| Southeast | Sunyshore City |
| Center | Veilstone City, Pastoria City, Eterna City, Canalave City and surrounding areas |
| Hyper-center | Celestic Town |
Underground, the hero can walk or run but can’t use the bicycle, and your Pokémon stay in their Poké Balls. You can play alone or with up to eight players, locally or online.
Digging
The tunnel walls hide treasure. Get close to a yellow dot on the map and press R to launch the radar: the walls you can dig start to glow. The game tells you how many treasures are inside, from two to four. You then dig with the hammer, which is precise, or the pickaxe, which clears more surface but weakens the wall faster. A crack at the top of the screen shows how sturdy the wall is: when it reaches the left edge, the wall collapses and you only keep the treasures that were fully uncovered.
| Category | Examples | Use |
|---|---|---|
| Spheres | Red, green, blue, pale and prism, sizes S and L | Currency for Underground vendors, Secret Base expansion |
| Evolution stones | Fire Stone, Water Stone, Thunder Stone, Leaf Stone, Moon Stone, Sun Stone, Oval Stone, Everstone | Evolutions |
| Fossils | Helix Fossil, Dome Fossil, Old Amber, Root Fossil, Claw Fossil, Skull Fossil (Brilliant Diamond), Armor Fossil (Shining Pearl) | To be revived at the Oreburgh Mining Museum |
| Plates | The sixteen elemental plates | Held items, Arceus forms |
| Strange Souvenir S and L | Once you have the National Pokédex | Slates for Ramanas Park |
| Chests | Fancy Chest, Luxury Chest | Pokémon statues, shiny ones in Luxury Chests |
| Miscellaneous | Star Piece, Heart Scale, Hard Stone, rocks and shards | Selling, held items |
Pokémon hideaways
Hideaways are large caverns populated by visible wild Pokémon that move around freely, much like the Wild Area in Sword and Shield. They open as soon as you get the Explorer Kit and shelter many species that aren’t found on the surface of Sinnoh, which makes them a must for completing the Pokédex and varying your team during the adventure.
The level of the Pokémon in the hideaways follows your progress:
| Progress | Levels encountered |
|---|---|
| Coal Badge | 16 to 20 |
| Forest Badge | 25 to 29 |
| Cobble Badge | 29 to 33 |
| Fen Badge | 33 to 37 |
| Relic Badge | 36 to 40 |
Levels keep rising with the following badges and after the Pokémon League. Some species only appear once you have the National Pokédex.
Statues and the Secret Base
Chests contain Pokémon statues. Displayed in your Secret Base, they influence the hideaways: each statue raises the chances of meeting Pokémon of its type, and a shiny statue, jade-colored, counts double. A base holds up to eighteen statues, placed on the floor or on pedestals sold by vendors.
To dig out a base, you need a drill. The Underground Man in Eterna City gives you one; others can be traded for ten S Spheres from vendors, with the requested color changing every day. The base can be expanded twice, in exchange for S Spheres and then L Spheres.
Underground vendors
Dressed as mountaineers, the vendors accept Spheres as payment. They offer statues, pedestals, drills and TMs. The TMs change every day, and so do their prices, but each one only asks for one color of Sphere. Some are only offered once you have a specific badge.
Multiplayer
The Grand Underground can be shared with up to eight players, locally or online. Other players dig alongside you and can visit your base. The online modes were added by update 1.1.0; they remain available with a Nintendo Switch Online subscription.
To go further: our Legendaries and Mythical Pokémon page explains what to do with Strange Souvenirs, and the complete walkthrough tells you when to go underground during the adventure.
