FFVI - Walkthrough - Terra's Scenario
Lete River continued
Party: 
The trio continue the raft ride on the Lete River. Again, make sure Banon doesn't kick the bucket or your game is over. At the end of the ride you find yourself a little east of Narshe, which is where you want to go.
Narshe/Mines
Chest: Rune Edge [in mines] (if you don't get this chest until the World of Ruin it'll become a Ribbon)
The guards won't let you in thru the main entrance so you'll have to find another way in. Remember the secret entrance Locke showed you? That's the way in. You're now in the mines. Go a little ways and you come to a follow-the-light-maze. If you make a mistake all you need to do is press the A button when the yellow light is in front of you. If you miss it you'll have to fight some enemies and then you'll have to start at the beginning of the maze again. The correct way through is:
E---| * = rocks
* | * S = Start
|---| |------| E = Exit
* | * | * | | & - = Correct path
|---| | |
| * * | * |
|-----S |--------|
Once you get past this maze you can reach a cave of Moogles (and a chest containing a Rune Edge or Ribbon if you wait) by going slightly out of your way. Remember where this cave is because later in the game Mog will join you here). Once you get out of the mines you will be back in Arvis' House where you started. You will talk a bit with Arvis and then the scenario will end.