Master Kohga escapes to another abandoned mine, and a friendly Construct tells you how to find it.
Quest Location
After your battle with Kohga, this quest will begin. The Kohga battle occurs during the A Mystery in the Depths quest. The location is -0821, -1940, -0523.
Get your Rewards
After the battle with Kohga's truck, open the chest to get a Huge Crystallized Charge, worth 100 Crystallized Charges. This will allow you to go to a crystal refinery, such as the one north of Lookout Landing, to increase your Energy Cell capacity.
The Steward Construct points out a lightroot in the distance where you can find the statues that will lead to the southwestern mine that Kohga mentioned.
Talk to the Construct nearby to get a Schema Stone. It will add the Fanplane schematic to your Autobuild list. The Construct will prepare the necessary materials to build it, so switch to Autobuild and select the Fanplane schema to build it automatically.
Go to the Lightroot
Place the Fanplane in the rail that points to the lightroot, then hit a fan to make it start moving. You can hit the fans again to allow the plane to glide down to the lightroot, but the fans will likely run out of power before you get there anyway.
When you reach Koradat Lightroot, examine the glowing object to create a teleport location here. The first statue is south of the lightroot.
Follow the statues and they will lead you southwest to Kawatik Lightroot at -1700, -3307, -0525.
From there, the statues lead you farther southwest, where you find South Lomei Depths Labyrinth, which you can optionally explore.
Otherwise, follow the statues from the labyrinth, which ead you west from there, then north, and then southwest to Amakawis Lightroot at -2426, -3337, -0465.
The path goes west from there, but it leads you directly to a Frox. If you want to avoid it, you can go to the slope that is just west of Amakawis Lightroot and use Ascend to get on top of it, then glide down to the area north of the Frox, past the gloom.
The statues lead you northwest at that point, and you eventually reach Mihcihc Lightroot at -3203, -3013, -0471.
From there, the statues lead west and slightly north, to the Abandoned Gerudo Mine at -3722, -2943, -0494. There are Yiga flying on Wings to look for you, so beware. You can get rid of these scouts if you find a Spring near them and hit it to launch yourself upward, then draw your bow to slow time, and hit the Yiga with arrows.
Fanplane Kohga
After that, go to the quest destination to find Kohga. When you approach him, there will be a cutscene, then he will go to the flat area nearby and board a Fanplane. See the Master Kohga: Fanplane Boss Strategy.
After Fanplane Kohga
After you defeat Fanplane Kohga, a chest will appear, and a Steward Construct will talk to you. Open the chest to get a Huge Crystallized Charge.
Before you go to the nearby lightroot, talk to the other Steward Construct in this area to get the Schema Stone for a Hovercraft. It doesn't fly upward; it just glides along the ground. It runs out of power quickly, so you might want to attach the nearby batteries to it. You can use it to go to where you can see lights to the southwest, and you will find a treasure chest.
Back at the mine, you will find a Large Poe on top of the Yiga building. Keep using Ascend to go farther up, and you will find Gonatoyros Lightroot at -3877, -2950, -0435.
Before you go, you can talk to the Forge Construct to be able to exchange Zonaite for device charges.
Reach the East Mine
The easiest way to reach the East Mine is to go to Mogawak Shrine in Zora's Domain, then go southwest down the waterfall, and go through the waterfall to find the Cave Under Zora's Domain, where you will find the Chasm Under Zora's Domain. Go down that chasm and you will reach the east mine, a.k.a. the Abandoned Lanayru Mine. Skip ahead to East Mine to find out what to do there.
If you can't or don't want to go to Zora's Domain, you can either go to the Lanayru Wetlands Chasm, which is north of Jonsau Shrine in the Lanayru Wetlands, or the East Hill Chasm, which is northeast of Kakariko Village.
If you go to the Lanayru Wetlands Chasm, you will find Uasnoj Lightroot south of where you land. If you go to the East Hill Chasm, you will find Takaruk Lightroot northeast of the chasm.
Lanayru Wetlands Chasm Route
The statues from Uasnoj Lightroot lead east, then northeast, where you can find Sekioam Lightroot at 2262, 0150, -0502.
The statues lead north from there, then northeast. You will be able to see Uinoj Lightroot in that direction. It's at 2918, 0508, -0795.
The statues go past a large arena, then they eventually lead southeast to the Abandoned Lanayru Mine. Kawagom Lightroot is south of the mine, at 3298, 0419, -0749.
East Hill Chasm Route
At Takaruk Lightroot (2360, -0510, -0589), there is a slope next to the nearby statue. Go up this slope and the statues lead northeast, then will lead southeast. The path then goes east and slightly north, and eventually there is a statue overlooking a cliff. If you look down from there, you can see Kegopa Lightroot, which is at 3886, -0215, -0608.
On the west side of Kegopa Lightroot, there is a statue nearby. You can look northwest to see more statues down below. Follow them, and you can optionally visit Ruto Canyon Mine to the southwest, where there are Zonaite Deposits and a treasure chest with a Large Crystallized Charge.
Back at the statues, follow them northwest. They lead to a tunnel, at the end of which you will find a couple of Grand Poes. Beyond that, you will find Kawagom Lightroot at 3298, 0419, -0749.
East Mine
Approach Kohga in the mine. There will be a cutscene, and then you will battle Kohga. See the Master Kohga: Raft Boss Strategy for details.
After Raft Kohga
Open the chest to get a Huge Crystallized Charge, then talk to the other Steward Construct to get the Bolt Boat design. You can build one with the materials that the Steward provides, then move the boat through the Octoroks to reach the nearby treasure chest, which contains a Large Crystallized Charge.
Find the Northwest Mine
As the Steward Construct said, it is rumored that there is a chasm that leads directly to the mine. Don't use Hyrule Chasm to try to go there, because although you will find statues there, they lead to a dead end.
Instead, go southeast from the Gatakis Shrine in Rito Village, and look down from the edge of the cliff and you will find Ponnick. Talk to him and he will show you the chasm. Glide into it and go down this chasm, which is called Rito Village Chasm. You will find the Abandoned Hebra Mine at the bottom.
Go west from the chasm to find Sikatag Lightroot.
Then go east to the quest location and you will find Kohga. Approach him and there will be a cutscene. Then Kohga will attack in an Ancient Construct. See the Master Kohga: Ancient Construct Boss Strategy.
After Ancient Construct Kohga
The quest is now complete. After the battle, open the two chests to get a Huge Crystallized Charge and a Diamond.
Talk to the other Steward Construct to get a Rocket Platform design. You can test it out with the parts that the Steward Construct provides. When the platform goes up, the rocket will eventually disappear, but the platform will stay in the air. After the rocket has disappeared, look northeast to see more platforms. These platforms will lead you to a treasure chest that contains a Large Crystallized Charge, and there are a couple of Crystallized Charges on the roof of the building behind the treasure chest. You can also reach a Grand Poe on the roof of the building where you fought Kohga.