Pokemon Heart Gold and Soul Silver - Walkthrough - Diglett's Cave Pokemon Heart Gold and Soul Silver: Walkthrough - Diglett's Cave
Before we proceed, make sure you have a Pokemon that has CUT with you.

1F:

Go down the ladder right in front of you.

B1F:

Follow the path, as it is pretty linear. Keep the DOWSING MCHN out to find useful items. We can't fully explore the area as we lack ROCK CLIMB, so for now I will just take you to the other side. For full info on this cave, see the exploration section.

At the end there is a ladder, take it to go up.

1F:

Go up the set of stairs to the left, and out the exit.
This walkthrough was written by MKaykitkats, used with permission.