In the Treasure of the Secret Springs side quest, there is a sleeping treasure in the mountains that needs to be awakened in Zelda: Tears of the Kingdom.
You must first find the hidden treasure which is somewhere near the three hot springs in the mountains. Then, to solve the puzzle, you must find a way to redirect all three springs in form of waterfalls to the treasure to awaken it from its slumber.
Completing this quest will reward you with Vah Medoh Divine Helm, a legendary headpiece worn by the first Rito champion during the rule of Rauru.
Talk to Tulin at his Home
Treasure of the Secret Springs side quest can only be started after completing the Tulin of Rito quest. Once the ice storms in Tabantha Tundra die down, return to Rito Village using the Gatakis Shrine.
Tulin is in his house at the following coordinates (-3610, 1822, 0218). He will tell you about a divine treasure and give you the following hint.
“Guide the three waters to that place. When it fills, the slumbering treasure will awaken once more.”
This will start the quest, and you can now select it from your journal.
Release Three Waterfalls in North Biron Snowshelf Cave
After beginning the quest, you need to make your way to the Biron Snowshelf located northwest of the Hebra Mountain Region. There is also a fast travel point of Eutoum Shrine close by that you can use.
If you can’t access the fast travel point, use the Rospro Pass Skyview Tower to glide northwest to reach Biron Snowshelf.
Once you reach the top of Biron Snowshelf, you will discover that the entrance to the cave is blocked by a large ice boulder. Hence, start by melting the blockade to clear the entrance. This can be done by using a fire weapon or fire arrows.
As you travel through the cave, it is advised to collect all the Bomb Flowers that come your way. After traveling a little, you will discover the tunnel is closed on the other end.
To get across, you need to use the Bomb Flower that you collected before. Doing so will make a hole in the tunnel, giving you access to the large chamber in the cave.
Once you are inside the chamber, you will notice several breakable boulders on the top of the chamber. These rocks can be rigged up using explosives. For that, you need to use the Bomb Arrows.
Use the upward draft to glide and hit the boulders with bomb arrows to release the waterfalls. This area has many ice Keese enemies, but don’t worry—the water in this area has healing properties.
If you successfully release all three waterfalls, a new path will open in the cave, which you can follow. The weight of the spring water will cause the large stone statue to move in the chamber, ultimately opening the path.
You now need to follow the newly opened path, and at the end of it, you will find a Treasure Chest. Once it is located, you must open the chest for the Vah Medoh Divine Helm. This armor piece has special cold resistance and yields two armor points.
Once you have the helm, return to Rito Village and tell Tulin. This will complete the Treasure of the Secret Springs side quest in Zelda: Tears of the Kingdom.
