Underground

Description
The Underground is unlocked when you purchase the Explorer Kit located in Cinnabar Island Shop. It also has its own currency called Diamonds that can be used to purchase upgrades for the Underground or Masterball at the Pokémon League. For more information about the Underground, open it by clicking on it after you purchased the Explorer Kit and click on the Help tab.

Upgrade Explanations

 * 1) Max Energy - Increases the maximum energy of the player
 * 2) Max Items - Increases the maximum amount of items that can spawn on a layer
 * 3) Min Items - Increases the minimum amount of items that can spawn on a layer
 * 4) Energy Restored - Increases the amount of energy regained by the player on each energy regeneration
 * 5) Energy Regeneration Time - Decreases the amount of time between each energy regeneration
 * 6) Daily Deals - Increases the amount of daily deals offered
 * 7) Bomb Efficiency - Increases the number of tiles destroyed with each bomb
 * 8) Survey Cost - Decreases the cost of the Survey ability
 * 9) Survey Efficiency - Increase the amount of layers Surveyed
 * 10) Larger Underground, +1 Max Item - Increases the Underground by two columns and two rows (1 on each side of the rectangle), Also increases the maximum amount of items that can spawn on a layer by one

Items

 * Note: Some Items can be dropped by Wild Pokémon as "Held Item Drops" in addition to being found in the Underground. These Items can also be rotated in any direction.

Efficiency
To find Underground items most efficiently, follow the format below, mining odd rows first:

Odd rows: 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 X 1 Even rows: X 2 X 2 X 2 X 2 X 2 X 2 X 2 X 2 X 2 X 2 X 2 X 2 X