Underground Exploration — Pokémon Diamond and Pearl Guide

Underground Exploration

The Grand Underground is a vast network of subterranean tunnels beneath the Sinnoh region, offering unique opportunities for item hunting, secret base customization, and even catching rare Pokémon. Access is granted early in your adventure, and mastering its mechanics will greatly benefit your journey.

Accessing the Grand Underground

You first gain access to the Grand Underground in Eterna City. After defeating Gardenia at the Eterna City Gym, head to the house next to the Pokémon Center. Speak with the old man inside, and he will give you the Explorer Kit. This key item allows you to descend into the Grand Underground from almost any outdoor location in Sinnoh. Simply select the Explorer Kit from your Bag to enter.

Mining for Treasures

Once underground, your primary activity will be mining for valuable items. Look for sparkling spots on the walls of the tunnels. Approach these spots and press 'A' to initiate a digging mini-game. You'll be presented with a grid and two tools: a pickaxe (for larger, slower digs) and a hammer (for smaller, faster digs). The goal is to uncover as many items as possible before the wall crumbles. The meter at the top indicates the wall's integrity; it decreases with each strike.

Here's a breakdown of common finds:

• Spheres: These come in various colors (Red, Blue, Green, Prism) and sizes. They are the currency of the Underground, used to trade with hikers for goods like traps and decorations for your Secret Base. Larger spheres are more valuable.
• Fossils: Extremely rare and valuable, these can be revived into ancient Pokémon at the Oreburgh Mining Museum. Keep an eye out for the following:
  • Armor Fossil: Exclusive to Pokémon Pearl. Revives into Shieldon.
  • Skull Fossil: Exclusive to Pokémon Diamond. Revives into Cranidos.
  • Old Amber: Revives into Aerodactyl.
  • Root Fossil: Revives into Lileep.
  • Claw Fossil: Revives into Anorith.
  • Helix Fossil: Revives into Omanyte.
  • Dome Fossil: Revives into Kabuto.
• Evolutionary Stones: Essential for evolving certain Pokémon. Look for:
  • Fire Stone
  • Water Stone
  • Thunder Stone
  • Leaf Stone
  • Moon Stone
  • Sun Stone
  • Dawn Stone
  • Dusk Stone
  • Shiny Stone
• Shards: Red, Blue, Green, and Yellow Shards can be traded for various TMs later in the game.
• Heart Scales: Used to teach forgotten moves to your Pokémon.
• Plates: Items like the Flame Plate or Splash Plate, which boost the power of certain type attacks when held by Arceus (though Arceus is not obtainable in Diamond/Pearl without glitches or events).
• Treasures: Items like Stardust, Star Piece, Big Pearl, and Nugget, which can be sold for high prices at Poké Marts.

Secret Bases

As you explore, you'll occasionally stumble upon small, empty rooms. These are potential locations for your Secret Base. To establish a base, simply interact with the glowing spot in the center of the room. You can then decorate your base with various items purchased from hikers using Spheres. Decorations can influence the types of Pokémon that appear in the Underground's Hideaways, so experiment!

To move your Secret Base, you'll need to purchase a Digger Drill from a hiker for a significant number of Spheres. Using the Digger Drill allows you to relocate your base to a new empty room.

Pokémon Hideaways

The Grand Underground is home to unique Pokémon not found on the surface. These Pokémon appear in specific "Hideaways" – larger caverns marked on your touch screen map. The types of Pokémon that appear in these Hideaways can be influenced by the statues you place in your Secret Base. For example, placing a Fire-type statue might increase the spawn rate of Fire-type Pokémon in nearby Hideaways.

Some notable Pokémon you can encounter include:

• Gligar (Diamond exclusive)
• Phanpy (Pearl exclusive)
• Teddiursa (Pearl exclusive)
• Mawile (Diamond exclusive)
• Absol
• Snorunt
• Swablu
• Tropius
• Bagon
• Gible (found in Wayward Cave, but also in specific Underground Hideaways)

These Pokémon are often at a higher level than those found on the surface early in the game, making them excellent additions to your team. Be prepared for battles!

Connecting with Friends

The Grand Underground also supports local wireless multiplayer. You can connect with nearby friends who are also in the Underground. This allows you to visit each other's Secret Bases, dig together in the same mining spots (which can yield more items!), and even set traps for each other in a friendly manner.

To connect, simply select "Connect with Friends" from the Underground menu. Your friends will appear as avatars on your map, and you can interact with them.