The Grand Underground is a vast and expansive area of Sinnoh in Pokémon Brilliant Diamond and Shining Pearl, and offers a significant amount to do in parallel to the main adventure.
While you don't need to go deep to complete the game, it's highly recommended, as there's content enough to keep you busy for hours. This is especially true after you've defeated the Pokémon League is beaten, with even more possibilities arising.
Here are four reasons you should invest more time into the Grand Underground.
You can catch rare Pokémon
The various biomes of the Grand Underground house some pretty rare Pokémon, such as Absol, Gible, and even Togepi.
You can also catch Starter Pokémon from the first four generations, as well as the key Pokémon Ditto.
You don't only have to rely on trades to get the other two starters in Pokémon Brilliant Diamond and Shining Pearl, thanks to improvements to The Great Underground.
Ditto is an incredibly useful Pokémon to own, especially when it comes to breeding. Here's where you'll find it in Brilliant Diamond and Shining Pearl.
You can build a Secret Base
By completing the Underground Man's tutorial tasks, you'll quickly learn all about mining and your Secret Base.
While you can't decorate it with household items like in the original, you can place statues - which will aid in the capture of several rare types of Pokémon.
Here's what you'll need to do to complete the Underground Man's tutorial of the Grand Underground in Pokémon Brilliant Diamond and Shining Pearl, from getting the Explorer Kit to discovering Pokémon hideaways.
You can collect valuable treasure
Mining the walls of the Grand Underground will reward you with much more than Spheres, Evolution Stones, and Statues for your Secret Base.
Sometimes you'll come across items called Shards, which are used to exchange for Slates in Ramanas Park.
These Slates are then used to call upon various Legendary Pokémon...
In order to summon Legendary Pokémon to Ramanas Park in Pokémon Brilliant Diamond & Shining Pearl, you're going to need special Slates. Here are the details.
You can catch loads of Shiny Pokémon
While the Masuda method and the Poké Radar are the easiest techniques to use when hunting for Shiny Pokémon, the Grand Underground is also a viable option.
All you need to do is collect the Digletts that you'll see as you're running about the tunnels.
Once you've hit 40 and the gauge is full, you'll have an increased chance of encountering Shiny Pokémon for a few minutes. Make sure to use it to your advantage, in conjunction with displaying statues in your base!
Are you wondering why you keep seeing Diglett and Dugtrio in the Grand Underground? Here's what they do in Pokémon Brilliant Diamond and Shining Pearl.