To obtain the “A Token of Friendship” side quest in The Legend of Zelda: Tears of the Kingdom, speak with Yona at Zora’s Domain after completing the Water Temple. For this quest, you’ll need to access the Ancient Zora Waterworks by jumping into the whirlpool in the East Reservoir Lake, which is southeast of Zora’s Domain.
Once inside, work your way through the area to the back right of the giant room where you’ll find a hole in the ground that you can jump in.
Do so then continue deeper into the waterworks where you’ll find the Stone Talus boss! If you wish, take it out by assaulting the blue ore deposit on its back.
When you’re ready to proceed, head behind the waterfall to find a chest containing Zora Greaves! Once you loot the chest, the quest will complete.