A large rift appears at Eldin Volcano, so you go northwest to investigate.
How to Reach Eldin Volcano
To reach Eldin Volcano, go to the southern gate of Hyrule Castle Town and go clockwise around the castle wall until you reach the bridge to the west. Cross it, then go south on the dirt road, and when it splits, go west, and at the next split, go north. Follow the dirt road and you will go past Hyrule Ranch. When the dirt road ends, go south to find another section of dirt road. The road will go west, then at the split, go northwest. The path leads to a Smoothie Shop, a Stamp Stand, and Kakariko Village. Be sure to check on the waypoint.
In Kakariko Village, go east from the covered well and approach the soldier talking to the people. There will be a cutscene.
You can jump and bind to the handle on the cover on the well, then move it left or right to open the well. Fall in and open the chest to get 3 bunches of refreshing grapes.
You can go into the dojo in the west part of town and talk to the guy in the middle to train. You can choose which training you would like to do.
You can talk to the old man northeast of the well to start the quest Questioning the Local Cats.
You can talk to the woman in front of the cucco pen west of the well to start the quest Cuccos on the Loose.
When you're ready to move on, go north from Kakariko Village, up the rocky slope. There will be a cutscene. This begins the quest The Rift on Eldin Volcano.