At the far west of the continent. Upon entering the cave, give "Star Ruby" to the golem; he'll let you pass.

Then pick up 4 items in the bottom room.

• (C-067) Mythril Helm: 1st chest.
• (C-068) 450 gil: 2nd chest.
• (C-069) 620 gil: 3rd chest.
• (C-070) Great Axe: 4th chest.

Exit the cave to another side of the mountain ranges.

There is only one path south, you'll see the cave at the end.

There is nothing really, except that you have to talk to the sage inside his room in the top-left corner. He'll give you Earth Rod.

Go back to the Cavern of Earth - B3, then use the "Earth Rod" behind the room to open a new entrance.

Bestiary checklist:

• (030) Gargoyle
• (032) Piscodemon
• (034) Mummy
• (035) Wraith
• (041) Earth Elemental
• (043) Wight
• (044) Ochre Jelly
• (045) Cockatrice
• (046) Vampire
• (049) Lich

There are 8 chests in this floor.

• Top room:
• (C-071) 5450 gil (Monster): 1st top chest.
• (C-072) 1520 gil: 2nd top chest.
• (C-073) Staff (Monster): 3rd top chest.
• (C-074) 3400 gil (Monster): 4th top chest.
• (C-075) 1455 gil (Monster): Bottom chest. 
  Bottom room:
• (C-076) 1250 gil (Monster): Top chest.
• (C-077) Mythril Shield (Monster): Middle chest.
• (C-078) Tent (Monster): Bottom chest.

There is nothing here, except a room on your left with a boss inside.