Written by MSG Commander
When you enter this dungeon for the first time, the game introduces Mining Points, places where you can collect crafting materials. Each Mining Point provides a random assortment of the crafting materials that are available in that location. (Each location has its own set of materials, and each Mining Point in a specific dungeon will give you some of the materials that are available there.)
Alia says you're here to look for Flame Moss, a strange substance that the residents of Laft use as a light source. The Flame Moss is (conveniently) located at the far end of the dungeon.
Back at Earthdepths Lake, go west to a side room that has Chain Mail. Equip the Chain Mail on Kline.
(You can begin strengthening the Chain Mail as soon as you can collect 6 Iron Ore Fragments, but you won't be able to evolve it until you find the right Recipe. Likewise, you can also begin strengthening the Long Sword, Battle Whip, Leather Vest, and Leather Guard once you have the materials for those, but again, you can't evolve them until you find more Recipes.)
Now go back to the entrance and follow the Map through exits A and B, collecting all the Mining Points along the way. When you reach the screen with gatekeeper, there's a bit of dialogue where Alia explains that he's there to keep people away. Ignore the gatekeeper, and explore the rest of the dungeon.
When you go through exit B, Alia tells you more about the tribes in Laft, and about the magic weapons used by the Lipsia Tribe. After the dialogue, go south. Take the northeast exit to a side room with a Mining Point, then go back and take the path to the south.
Go past the south exit, and take the next exit to the east to get another treasure.
Now go back, and take the exit to the south. The Flame Moss is in this room. Alia says it needs to be refined into Blazing Sand, and in order to do that you need to go to Enesen Hamlet. After the dialogue, collect the Mining Points, and then Exit the dungeon and go to Ensen Hamlet.