Legend of Zelda: The Twilight Princess
Walkthrough — IX. Go Fish and Dabbling in Cryptozoology

During the amazing cut-scene after the dungeon, you’ll be instruction to seek out mirror shards in the mountains, forest, and the sky. Logically, that means we start with the sky.

To get to Snowpeak Province, the mountains in question, warp to the waterfall basin in Zora’s Domain. Talk with a few of the Zoras there, who will all mention that the snow monster from Snowpeak has been visiting the basin recently. How wonderful. Now, head through the cavernous opening on the east wall to enter Snowpeak. Beyond you’ll meet the snow monster—oh, wait, no, that’s Ashei. She’ll explain the snow monster has been visiting the basin (which we know) and that he seeks Reekfish during his visit (that’s new). She’ll also give Link a sketch she drew of the monster.

Now, we need to learn how to catch Reekfish. Talk to the Zora guard at the entrance to Snowpeak and show him the sketch and he’ll mention that Prince Ralis is best at catching Reekfish. As such, we need to track down the heir apparent of the Zora, who should be staying in Kakariko where we last left the little guy.

Warp to Kakariko and head to the graveyard where you found the Zora Armor to seek Ralis praying at his mother’s grave. Ralis will tell you that a Reekfish can only be caught with a special coral hook, which conveniently his earring is one of. He’ll give you the earring, which will be attached to your fishing rod immediately thereafter.

Return to the waterfall basin and fish in the spot indicted, in the northwest corner of the basin behind the large pillar-shaped rocks. You’lls ee little red fish swimming in the water below. Cast your line into the water, and eventually you’ll capture a Reekfish (no bait required). Immediately once you catch the fish you’ll drop it on the ground, so quickly switch to wolf form and sniff the fish (a prompt will appear on screen) and learn the Reekfish Scent. Now, switch the Sense mode, and follow the scent to Snowpeak.

Follow the scent all the way up the mountain. At one point you’ll come to a seeming dead end, a large snow bank-capped wall. Run into the wall to collapse the bank and provide a way up to the summit. In the next area you’ll discover a howling stone, and beyond that by the frozen tree the snow monster in question.

Transform into a human and speak with him. As Yetto (yes, that’s his name) explains it, he only wanted to get the fish to make a soup for his sick wife. He’ll explain that he lives in the manor at the very edge of the mountain range, and to get there you will have to play a snowboarding challenge. Ram into the tree, and snowboard down the hill. Eventually you’ll come to the Snowpeak Manor.

Enter to begin this very unorthodox of dungeons.