Delving Deep into the Grand Underground

A New World Awaits beneath Sinnoh’s Surface

Players of the Pokémon Brilliant Diamond and Pokémon Shining Pearl games will be in for a pleasant surprise when they fire up their Explorer Kit for the first time and arrive in the renamed-and-revamped Grand Underground. The Sinnoh region’s subterranean network of tunnels has been powered up to include scores of cavernous hideaways teeming with catchable Pokémon. From Fossil digging to Secret Bases, nearly the entire underground experience has been refined for the Pokémon Brilliant Diamond and Pokémon Shining Pearl games. It’s time to explore what exactly is going on beneath your feet...

Accessing the Grand Underground

You can begin exploring the Grand Underground once you reach Eterna City. Simply speak to the Underground Man at his home next door to Eterna’s Pokémon Center to receive your very own Explorer Kit. But we’re not done with the Underground Man yet—and he’s not done with you! To ease you into the spelunker’s life, he’ll offer you four short missions. After you complete each task, revisit the Underground Man to receive his next request as well as your reward for a job well done.

Use the Explorer KitRed Sphere S, Blue Sphere S, Green Sphere S
Dig up an objectDigger Drill
Make a Secret BaseQuick Ball ×5, Dusk Ball ×5, Dive Ball ×5
Decorate your Secret BaseSquare Pedestal XS

The Zones of the Grand Underground

The Grand Underground’s many tunnels, caves, and caverns are divided into seven zones. When you first use the Explorer Kit in Eterna City, you’ll arrive in a sprawling section of the Grand Underground comprised of two connected parts: the Eastern Zone and Western Zone. Stretching across both sides of Sinnoh, these zones contain no fewer than 26 Pokémon Hideaways spanning nine different terrains (see full a description of each below), along with three vendors who will be happy to exchange the spheres you’ve collected for a number of useful items.

While varied, The Eastern and Western Zones’ caves and caverns don’t include every type of terrain, so there are limits to the Pokémon you can initially find within Pokémon Hideaways. To see everything the Grand Underground has to offer, you’ll also need to find a way into the Central Zone, the Northwestern Zone, the Northeastern Zone, the Southwestern Zone, and the Southeastern Zone. To reach a specific zone, you’ll have to use your Explorer Kit from different areas of the Sinnoh region’s surface. Many of these zones are only accessible from specific locations, some of which are among the final areas you’ll be able to visit on your adventure.

Not only does every zone host at least one rare terrain, their hideaways also offer different items to find, including rare items needed for Evolution. Additional items may appear as you progress through the game, so keep those eyes open!

Grand Underground Zone(s)Access Point
Eastern and Western ZonesEterna City, Hearthome City, Veilstone City, etc.
Central ZoneCelestic Town
Northwestern ZoneSnowpoint City, Fullmoon Island
Northeastern ZoneBattle Zone
Southwestern ZoneTwinleaf Town, Jubilife City, Canalave City, etc.
Southeastern ZoneSunyshore City

The Eastern and Western Zones

The first available section of the Grand Underground is massive, allowing access to nine of the eleven terrains and two different caverns to explore: Still-Water Cavern and Big Bluff Cavern. The Eastern and Western Zones are accessible from many of the towns and routes on Sinnoh’s main land mass. As soon as you can access these zones, you should be able to pick up TM34 (Shockwave) in the Big Bluff Cavern, plus TM09 (Bullet Seed) and a Big Mushroom in the Still-Water Cavern. You can also find TM04 (Calm Mind) and TM37 (Sandstorm) in the Rocky Caves, as well as TM87 (Swagger) in a Fountainspring Cave.

The Central Zone

The hole in the donut that is the Grand Underground, this small middle area is only accessible from Celestic Town. The Central Zone is home to just two caves and one cavern, but it offers your only chance to visit an Icy Cave (and snag a rare Deep Sea Scale) early in the game. Don’t miss TM59 (Dragon Pulse) and a Nugget in the large Stargleam Cavern, either.

The Northwestern Zone

You can enter this chilly zone from Snowpoint City, but that’s not its only access point. After receiving the National Pokédex, you can return to Canalave City and speak to the boat captain in the house that’s closest to the local Pokémon Center. From there, you can travel to Full Moon Island. Once you’ve arrived, use your Explorer Kit to access the Northwestern Zone, where Icy Caves and Whiteout Caves full of Ice-type Pokémon are common. In the Whiteout Caves you can pick up a Sharp Beak and a Dawn Stone, while the large Glacial Cavern offers Leftovers and TM80 (Rock Slide).

The Northeastern Zone

Accessible from anywhere in the Battle Zone, this hot and dry section of the Grand Underground is home to Volcanic Caves, Sandsear Caves, and the Typhlo Cavern. Item highlights in the Northeastern Zone include TM49 (Scald) and TM50 (Overheat) from the Volcanic Cave, TM71 (Stone Edge) in the Typhlo Cavern, a Twisted Spoon in the zone’s lone Dazzling Cave, and a Shiny Stone in the Spacious Cave.

The Southwestern Zone

This wet, grassy zone provides ample opportunity to catch Grass-type and Water-type Pokémon. It also offers your first chance to visit Swampy Caves. The big prizes here include a Deep Sea Tooth in the Fountainspring Cave, TM01 (Focus Punch) and TM06 (Toxic) in the Swampy Caves, and a Rare Candy in the Spacious Cave south of the large Sunlit Cavern.

The Southeastern Zone

The zone that’s accessible from Sunyshore City features a few rare terrains, including a Sandsear Cave and two Fountainspring Caves. But mostly the Southeastern Zone is just one big bog, with three Swampy Caves and even more swampy goodness in its Bogsunk Cavern, which has a lot of water to surf through in search of aquatic Pokémon. You can also pick up TM19 (Giga Drain) and a Dusk Stone there, as well as TM39 (Rock Tomb) in a nearby Rocky Cave.

Catching Pokémon in Caves and Caverns

The biggest change from the Underground of Pokémon Diamond and Pokémon Pearl is the addition of caves and caverns called Pokémon Hideaways. These hideaways are home to just over 200 different species of Pokémon, many of which only appear on Sinnoh’s surface after you’ve acquired the National Pokédex. Not all of these Pokémon will be available on your first visit to the Grand Underground, but more species will begin to appear as you progress through the game. Also note that some Pokémon found in hideaways are exclusive to either Pokémon Brilliant Diamond or Pokémon Shining Pearl.

Each “?” icon displayed on the Grand Underground Map represents a Pokémon Hideaway that features one of eleven different terrains. These terrains range from sunlit fields to volcanic craters, and each is home to a different variety of Pokémon. Whenever you enter a hideaway for the first time, the name of the cave or cavern will be displayed as the “?” icon on the map is replaced with an icon indicating its terrain. A given terrain will house the same selection of Pokémon whether the hideaway is a smaller cave or a larger cavern. But because the caverns are larger, they can house more Pokémon at a time and give you more room to maneuver, making it easier to track down a particular Pokémon you want to catch. Some terrains are common throughout the Grand Underground, while others are limited to a select few hideaways.

What truly sets Pokémon Hideaways apart from Sinnoh’s surface is that you can actually see wild Pokémon wandering freely around the environment, allowing you to pick and choose which ones you want to encounter. Every time you exit and reenter a hideaway, it will be repopulated with a new selection of the Pokémon that can appear in that terrain. Keep in mind that wild Pokémon in the Grand Underground are quite tough—if you enter a hideaway as soon as you receive your Explorer Kit, you’ll be facing Pokémon that average around level 28, and their levels will increase further as you earn more Gym Badges and ultimately become the Pokémon League Champion.

Stock up on Dusk Balls! No matter how well-lit a cave or cavern may be, you’re still underground where Dusk Balls will serve you well.

Your fishing rods won’t work in the Grand Underground, but there are aquatic Pokémon you can only reach with the hidden move Surf.

Pokémon Hideaways
and the Terrains Inside

Spacious Caves

These common hideaways can be found in every zone of the Grand Underground. Pokémon of every type gather in Spacious Caves, but they’re especially popular with Normal types. Lickitung, Aipom, and Skitty are all exclusive to this terrain. In the early stages of your adventure—when other terrains still offer a limited selection of Pokémon—Spacious Caves offer a diverse array of useful catches like Machop, Houndoom, Wingull, Shinx, and Buneary. It’s also a good place to find Bagon and Shelgon in Pokémon Shining Pearl.

Grassland Caves and Sunlit Cavern

These green and beautiful hideaways host the largest variety of Pokémon—over 80 different species total! Naturally, this terrain is a favorite among Grass types, and it’s the only terrain in the Grand Underground where you can catch Hoppip, Skiploom, Sunkern, Seedot, Nuzleaf, Combee, and Cherubi. Here you can find Scyther in Pokémon Brilliant Diamond or Pinsir, Lotad, and Lombre in Pokémon Shining Pearl. It’s also a great place to look for Grass-type first partner Pokémon like Bulbasaur, Chikorita, Treecko, and Turtwig.

Fountainspring Caves

The crystal-clear waters in these hideaways attract Water types, while their grassy shores appeal to many of the same Grass types that frequent Grassland Caves. Despite some overlap in wild Pokémon options, this is the only terrain where you can catch Dratini, Shellos, and Gastrodon. Other rare Pokémon that reside here include Chinchou, Lanturn, Octillery, and Surskit. Fountainspring Caves are also great places to look for Water-type first partner Pokémon like Squirtle, Totodile, Mudkip, and Piplup.

Rocky Caves and Big Bluff Cavern

The sandy desert terrain found in these hideaways is especially popular with Normal types, Ground types, and Rock types. It’s the only terrain in the Grand Underground where you can catch Phanpy in either game, along with Gligar, Larvitar, and Pupitar in Pokémon Brilliant Diamond. In the early stages of your adventure, it’s a great place to catch Rhyhorn, Absol, and Skorupi. As your journey progresses, this terrain will become popular with an array of Pokémon including Zigzagoon, Trapinch, Vibrava, Baltoy, Hippopotas, and more.

Volcanic Caves

It probably won’t surprise you to learn that the rivers of lava in these sweltering hideaways are popular with Fire types. In the early stages of your adventure, you can catch Vulpix and Ponyta in both games, as well as Growlithe in Pokémon Brilliant Diamond or Magby in Pokémon Shining Pearl. As your journey progresses, they’ll later be joined by Numel, Torkoal, and others. There are also Normal types like Sentret and Furret and Rock types like Geodude and Onix. Once you’ve become the Pokémon League Champion, you can search this terrain for Fire-type first partner Pokémon like Charmander, Cyndaquil, Torchic, and Chimchar.

Swampy Caves and Bogsunk Cavern

These hideaways are great places to search for Swamp-type Pokémon... Wait, no, that’s not a thing. But the Pokémon that gather in this terrain do tend to include Water types, Poison types, and Ground types, such as Grimer, Wooper, Quagsire, Barboach, and Croagunk—the last of which you’ll need the hidden move Surf to reach. There are also several Grass types and Bug types to find, such as Pineco, Roselia, and Tropius. Pokémon that appear exclusively in this terrain include Weezing, Tangela, and Tangrowth.

Dazzling Caves and Stargleam Cavern

The enchantingly crystalline terrain found in these hideaways is home to an eclectic mix of Psychic types, Ghost types, and Fairy types. Despite this terrain being somewhat rare, there’s a long list of Pokémon that will only appear here, including Kadabra, Gastly, Hypno, Togepi, Wobbuffet, Girafarig, Snubbull, Ralts, Kirlia, Duskull, and Dusclops. You can also find Mawile in Pokémon Brilliant Diamond or Misdreavus and Sableye in Pokémon Shining Pearl. Keep in mind that this is the only terrain where you can catch Ditto, a Pokémon that’s crucial for Trainers hoping to discover rare Pokémon Eggs.

Whiteout Caves

These hideaways feature one of the Grand Underground’s two cold-weather terrains, both of which share many of the same Pokémon. You can expect to find plenty of Ice types here, including Sneasel, Swinub, Delibird, Snorunt, Glalie, Walrein, and Snover. Spheal and Sealeo can also be found in Pokémon Shining Pearl. Of course, you can still find plenty of non-Ice types like Magnemite, Tauros, Mareep, Meditite, Pachirisu, and more. Notably, you can catch both Beldum and Munchlax here with relative ease—two of the hardest Pokémon to track down in the original releases of Pokémon Diamond and Pokémon Pearl.

Icy Caves and Glacial Cavern

The terrain in these beautifully frozen hideaways is found primarily in the Grand Underground’s Northwestern Zone. In addition to the Ice types shared with the Whiteout Caves listed above, wild Pokémon here include Mr. Mime, Smoochum, Swablu, Buneary, and Bronzor, as well as Poochyena and Mightyena in Pokémon Brilliant Diamond. The hidden move Surf can take you across those freezing-cold waters in search of Pokémon like Staryu and Lanturn

Riverbank Caves and Still-Water Cavern:

As the terrain icon suggests, these hideaways are something of a mix between the Grassland Caves and the Fountainspring Caves. Nearly 80 different Pokémon species call this terrain home, including all the Grass-type and Water-type first partner Pokémon listed earlier: Bulbasaur, Squirtle, Chikorita, Totodile, Treecko, Mudkip, Turtwig, and Piplup.

Sandsear Caves and Typhlo Cavern

These hideaways’ mixed terrain is like a second home to many of the wild Pokémon from the Grand Underground’s Volcanic Caves and Rocky Caves. As the name of the large Typhlo Cavern in the Northeastern Zone suggests, this is the perfect destination for Typhlosion fans, as Cyndaquil—the Fire-type first-partner Pokémon whose final Evolution is the cavern’s namesake—can be caught here along with other Fire-type first partner Pokémon like Charmander, Torchic, and Chimchar.

Other Denizens of the Deep

Wild Pokémon aren’t the only ones that like to gather beneath Sinnoh’s surface. You’ll also encounter vendors, healers, and other friendly faces in the network of tunnels that link the Grand Underground’s caves and caverns. At least one vendor can be found in each zone, but their stock—which changes daily—will be the same no matter which zone you visit. Instead of money, these vendors use spheres of various colors and sizes as currency. Vendors can give you items in exchange for your spheres, or they can give you spheres in exchange for any unwanted items you’ve dug up. Some vendors deal in small spheres while other vendors deal in large spheres, but they both offer a daily selection of pedestals and TMs. Small-sphere vendors also sell Digger Drills for when you want to move your Secret Base (more on that below).

Catching Spiritomb with a Little Help

The named nonplayer characters (NPCs) you’ll find wandering through the Sinnoh region’s subterranean tunnels provide something much more valuable than battles or advice. Spiritomb, a rare Ghost- and Dark-type Pokémon, can only be caught by exploring the Grand Underground—and you can’t do it without a little help. Before the Forbidden Pokémon will materialize, you must talk to a combined total of 32 different players and NPCs—excluding vendors and healers—in the Grand Underground. In a change from the original Pokémon Diamond and Pokémon Pearl, both human players and NPCs count toward the 32 encounters needed to summon Spiritomb. If you’re unable to explore the Grand Underground with other players through your Nintendo Switch system’s online communication features, don’t worry! You can still meet your quota by adding NPC interactions to your grand total. If player interactions are off the table, there are enough NPCs scattered across these underground tunnels to finish the job—you’ll just have to thoroughly explore all seven zones if you want to find them all.

To catch Spiritomb, you’ll first need an Odd Keystone. A character near the Honey tree on Route 208 will give you one, but you can also dig up Odd Keystones in the Grand Underground or find one in hidden in Twinleaf Town. After you’ve got your hands on one, stand near the Hallowed Tower—a small stone cairn in the southeast corner of Route 209—and use the Odd Keystone from your Bag’s Other Items pocket. If you try this out before you’ve talked to any Trainers underground, you’ll just see a message saying that the Hallowed Tower appears to have been built many years ago. But as you meet other players and NPCs beneath Sinnoh’s surface, that message will begin to change. Once you’ve finally spoken to 32 unique players or NPCs, use the Odd Keystone near the Hallowed Tower and the Forbidden Pokémon will appear with a ghostly wail. You’ll only have one chance to catch Spiritomb per Odd Keystone, so make sure you save your game first!

Fossil Digging from Tunnel Walls

The walls of the Grand Underground’s tunnels are literally bulging with treasure. Look for golden sparkles on the Grand Underground Map, and press the R Button when you’re near one of those yellowish spots to make the sparkle appear on-screen. Examine the spot to learn how many items are hidden there and start digging. The positions of these digging spots reset whenever you enter the Grand Underground or exit a Pokémon Hideaway, so you’ll never run out of places to dig.

Pokémon Fossils and other treasures are hidden beneath up to four layers of rock, and you’ll need to use your sledgehammer and pickax to excavate them. Use the R Button to switch between tools. Each swing of a tool weakens the wall, as indicated by the crack forming at the top of the screen. When the crack reaches the other side of the screen, the wall will collapse, and only the treasures you’ve fully uncovered will be yours to keep.

The sledgehammer can break through a wider area of the wall, but in the process it weakens the wall more than a swing of the pickax. As a general rule, you want to use the sledgehammer first, tapping around the wall until you expose pieces of each of the treasures hinted at when you began digging. Once you see all the treasures available in this digging session, you can use your pickax to focus on uncovering the ones you want most. Sometimes there are strips of bedrock in the deepest level of the wall, which cannot be excavated further—listen for the clink of metal on stone so you don’t mistake it for an item.

Spheres, Boxes, and Other Treasures

There’s a staggering variety of treasures hidden within the tunnel walls. Most often, you’ll find spheres, which come in five varieties: Red, Blue, Green, Pale, and Prism. Each color of sphere comes in small and large sizes, with the larger ones being more valuable. You can then trade your spheres to the vendors found throughout the Grand Underground for TMs and other items.

The second-most common items you’ll find are stone boxes, which can be opened to reveal Pokémon statues that you can use to decorate your Secret Base. Stone boxes come in a few different varieties—the prettier the box, the rarer the statue you’ll find inside. Rare statues obtained from Gorgeous Stone Boxes come in a more lustrous texture and impart a stronger effect when set up in your Secret Base. (See “Decorating Your Secret Base” for more details.)

The most exciting treasures you can find underground are Pokémon Fossils, which can be taken to the Mining Museum in Oreburgh City and turned into living, breathing Pokémon. Initially, only one Fossil can be found per game: the Skull Fossil (Cranidos) in Pokémon Brilliant Diamond and the Armor Fossil (Shieldon) in Pokémon Shining Pearl. But after you’ve received the National Pokédex, you’ll be able to dig up Helix Fossils (Omanyte), Dome Fossils (Kabuto), Old Ambers (Aerodactyl), Root Fossils (Lileep), and Claw Fossils (Anorith).

Finally, there’s a wide variety of accessories, Evolution stones, and other rare items that can be dug up underground. These include power-boosting held items called Plates for each Pokémon type, as well as shards found in four different colors. You can trade 10 shards of the same color to an NPC on Route 212 in exchange for TMs containing weather-changing moves.

Treasures to Be Found in the Grand Underground

TreasureUseTrade Value
Red ShardTrade 10 on Route 212 for TM11 (Sunny Day)Red Sphere S ×16
Blue ShardTrade 10 on Route 212 for TM18 (Rain Dance)Blue Sphere S ×16
Yellow ShardTrade 10 on Route 212 for TM37 (Sandstorm)Prism Sphere S ×16
Green ShardTrade 10 on Route 212 for TM07 (Hail)Green Sphere S ×16
Sun StoneMakes certain species of Pokémon evolveRed Sphere S ×24
Moon StoneMakes certain species of Pokémon evolveRed Sphere S ×12
Fire StoneMakes certain species of Pokémon evolveRed Sphere S ×24
Thunder StoneMakes certain species of Pokémon evolvePrism Sphere S ×12
Water StoneMakes certain species of Pokémon evolveBlue Sphere S ×24
Leaf StoneMakes certain species of Pokémon evolveGreen Sphere S ×24
Oval StoneMakes certain species of Pokémon evolveRed Sphere S ×24
Heart ScaleGive to the Move Tutor in Pastoria to relearn a forgotten moveRed Sphere S x8
Odd KeystoneUsed to summon Spiritomb on Route 208 (see above)Green Sphere S ×24
EverstoneHeld item that prevents a Pokémon from evolvingPale Sphere S ×12
Hard StoneHeld item that boosts the power of Rock-type movesRed Sphere S ×24
Light ClayHeld item that extends the duration of barrier moves like Light Screen and ReflectRed Sphere L ×15
Iron BallHeld item that cuts Speed and makes Flying-type Pokémon vulnerable to Ground-type movesPrism Sphere L ×15
Icy RockHeld item that extends the duration of the move HailPale Sphere L ×10
Smooth RockHeld item that extends the duration of the move SandstormPrism Sphere L ×10
Heat RockHeld item that extends the duration of the move Sunny DayRed Sphere L ×30
Damp RockHeld item that extends the duration of the move Rain DanceBlue Sphere L ×30
Flame PlateHeld item that boosts the power of Fire-type movesRed Sphere L ×40
Splash PlateHeld item that boosts the power of Water-type movesBlue Sphere L ×40
Meadow PlateHeld item that boosts the power of Grass-type movesGreen Sphere L ×40
Zap PlateHeld item that boosts the power of Electric-type movesPrism Sphere L ×20
Icicle PlateHeld item that boosts the power of Ice-type movesBlue Sphere L ×40
Fist PlateHeld item that boosts the power of Fighting-type movesPrism Sphere L ×20
Toxic PlateHeld item that boosts the power of Poison-type movesPale Sphere L ×20
Earth PlateHeld item that boosts the power of Ground-type movesGreen Sphere L ×40
Sky PlateHeld item that boosts the power of Flying-type movesBlue Sphere L ×40
Mind PlateHeld item that boosts the power of Psychic-type movesPale Sphere L ×20
Insect PlateHeld item that boosts the power of Bug-type movesGreen Sphere L ×40
Stone PlateHeld item that boosts the power of Rock-type movesPrism Sphere L ×20
Spooky PlateHeld item that boosts the power of Ghost-type movesPale Sphere L ×20
Draco PlateHeld item that boosts the power of Dragon-type movesRed Sphere L ×40
Dread PlateHeld item that boosts the power of Dark-type movesRed Sphere L ×40
Iron PlateHeld item that boosts the power of Steel-type movesPrism Sphere L ×20
Pixie PlateHeld item that boosts the power of Fairy-type movesPale Sphere L ×20
Root FossilCan be used to revive a fossilized Pokémon (Lileep)Green Sphere S ×32
Claw FossilCan be used to revive a fossilized Pokémon (Anorith)Red Sphere S ×32
Helix FossilCan be used to revive a fossilized Pokémon (Omanyte)Blue Sphere S ×32
Dome FossilCan be used to revive a fossilized Pokémon (Kabuto)Blue Sphere S ×32
Old AmberCan be used to revive a fossilized Pokémon (Aerodactyl)Green Sphere S ×32
Armor FossilCan be used to revive a fossilized Pokémon (Shieldon)Blue Sphere S ×32
Skull FossilCan be used to revive a fossilized Pokémon (Cranidos)Green Sphere S ×32
Star PieceCan be sold at a high price to shopsPale Sphere L ×10
Rare BoneCan be sold at a high price to shopsPale Sphere S ×12

Decorating Your Secret Base

The Underground Man will walk you through the process of creating your Secret Base, which is a simple matter of using a Digger Drill on an empty patch of wall in the Grand Underground’s tunnels. The next step is to start decorating your Secret Base with all the statues you’ve found from digging up stone boxes. Select the glowing orb at the entrance to your base to choose and arrange your statues. You can put your favorite statues on similarly sized pedestals (also available from underground vendors) if you’re classy like that. You’ll also be able to move your Secret Base—all decorations intact—by using another Digger Drill, which you can buy from the vendors who trade for small spheres.

As you decorate your Secret Base, you’ll notice the orb at its entrance changing colors to reflect which Pokémon type is most prevalent among the statues you’ve set up. If you check the effect of those statues, you’ll see that they’ve boosted the appearance rate of wild Pokémon of the same type that you’ll encounter in hideaways. The more statues you set up of a single Pokémon type, the greater this boost will be. Rare statues found in fancier stone boxes will boost this appearance rate even higher.

Expanding Your Secret Base

If your Secret Base is feeling a little cramped, one of the underground vendors can increase its size twice. All they ask in exchange for these modest upgrades is a ludicrous number of spheres—welcome to the modern real estate market! Each expansion will give you a little more room to work with, but it will not increase the maximum number of statues (18) that you can place in your Secret Base at once.

ExpansionSphere Cost
First ExpansionRed Sphere S ×60, Blue Sphere S ×60, Green Sphere S ×60, Prism Sphere S ×30, Pale Sphere S ×30
Second ExpansionRed Sphere L ×40, Blue Sphere L ×40, Green Sphere L ×40, Prism Sphere L ×20, Pale Sphere L ×20