After you find the cable car to Mt. Chimney blocked, you have to go through Fiery Path to reach northern Route 111.
Explore the Route
Go northeast from the entrance of the route to find Ace Trainer Wilton, who has Electrike, Bagon, and Makuhita.
Go north and you find Aarune. He tells you about Super Secret Bases and gives you TM94 Secret Power. He'll use Secret Power to reveal the Secret Base entrance in the nearby tree, then you'll take a look in the base. While there, he'll ask you what for a phrase that you say when you are happy. Afterward he makes a Secret Base for you in the tree.
He explains that you can use the PC in the base to take out any decorations that you have and put them into your base.
He also says that if you find someone else's base, be sure to take their flag.
Aarune says that there is a Secret Base Guild in Fortree, and you can visit him there.
After Aarune departs, you can use the PC in the base to decorate it, manage QR codes (where you can also generate the QR code of your base), edit your settings, and more. You can find other players' bases through StreetPass, or by scanning in the QR Codes of other players' bases.
For more information, read the Super Secret Bases Guide.
Outside, you can go east, and if you have a pokémon with you that knows Cut, you can cut the tree to the east and reach the Old Lady's Rest Stop. Just talk to the old lady and she will let you and your pokémon rest here.
Otherwise, you will need to go northeast. You will pass by Fairy Girl Cece, who has Spoink and Mawile.
Farther northeast, there are a few berry trees. The girl nearby will give you a berry, too.
Then you can head southeast to find the Old Lady's Rest Stop if you haven't been there already. Talk to the old lady to heal up your pokémon.
North of the old lady's house, if you have the Mach Bike you can ride up the slope to reach the cliff.
Go south on the cliff to find Backpacker Deon, who has Linoone.
South of Deon, there is an Elixir.
West of the cliff, you will encounter Ace Trainer Brooke, who has Wingull, Numel, and Roselia.
Go west from Brooke and you will reach Route 113.