As you explore Great Sky Island, you discover Pondside Cave east of In-Isa Shrine.
Pondside Cave is east of In-Isa Shrine.
Explore the Cave
Defeat the Keese in the cave. You can attach Keese Eyeballs to arrows to add a homing effect, or attach Keese Wings to arrows to make them go farther. Then use the Boulder Hammer on the ore deposit.
Go farther ahead and you will find a creature called a Bubbulfrog. Defeat it to get a Bubbul Gem.
There are cracked boulders in the eastern wall of the room with the Bubbulfrog. You can break them down to find a rare ore deposit.
There is a tunnel going north from the room with the Bubbulfrog. It leads to a chest that contains an Archaic Tunic.
From there, go east to go outside. Here you can talk to Rauru, and the nearby Maker Constructs. You will learn that the Fans on the ground can be powered by your Energy Cell. Hold the L button and switch back to Ultrahand, then build a raft, and attach a fan to the back of the raft. Note that if you try to use the materials in front of the Contructs, they will stop you, so go over to the other logs farther away and use them instead.
Place the raft in the water, then jump onto the raft and hit the fan (but try to avoid hitting the logs, which will break if they take too much damage). Hitting the fan will activate it, and it will start to use up the energy in the Energy Cell. When you reach the other side, be sure to hit the fan again to deactivate it so that it will stop using energy.
On the other side, you can talk to the Construct to learn about starting a fire and cooking. Go to the cookpot nearby and you will see some flint on the ground next to it. (If you lose the flint, just drop another on the ground next to the cookpot.) Hit the flint with a metal weapon to start the fire under the cookpot, and then you can use it to cook.
Go up the nearby stairs (north of the cookpot) and you will see some stones in a pit in the ground. If you jump and swing the Boulder Hammer, you will break through the rocks and fall into an area below. Shoot the balloon in this area to find a Korok. Then climb up the wall to go back to the area above.
Make your way up the stairs. Before you go into the cave at the top, you can find some Constructs in the area to the side. Defeat them and open the chest that unlocks, and you will get an Opal.
Then go into the cave. This is Mining Cave.