Before you can properly explore the Castor Wilds, you'll need two crucial items. The Pegasus Boots are found in the Shoe Shop in Hyrule Town after completing a Kinstone Fusion with the Hurdy-Gurdy Man. The boots allow you to dash, which is essential for crossing quicksand and breaking certain blocks.
The Roc's Cape is typically found in the Wind Ruins, an area leading to the Fortress of Winds. It allows Link to jump over gaps and enemies. With both items, the Castor Wilds become navigable. Practice using the dash and jump mechanics together, as many puzzles and combat encounters will require their combined use. These items not only aid in traversal but also open up new combat strategies, allowing you to evade attacks and reach elevated enemies. Mastering these new movement options is key to progressing.