Its exterior debuts in Chapter 218.
- Marge causes a cave-in and searches for the Red Orb
- Ruby saves Riley
- Marge and Ruby battle
- Marge invites Ruby to join Team Magma
- Ruby escapes from Marge, and Marge decides to get revenge
Mechanical construction of the tunnel was halted because it was bothering the wild Whismur, so construction (led by Riley) has been continued by hand.