Whistling Hill Cave can be found just north of Teniten Shrine in Hyrule Field.
Cave Location
Whistling Hill Cave can be found at -0079, -1042, 0019 in Hyrule Field, near Teniten Shrine.
Cave Features
As you go down the slope into the cave, two Keese attack. When you reach the first room of the cave, two more Keese attack. Look at the ceiling to see this cave's Bubbulfrog.
There is a tunnel in the southwest part of the cave that is blocked by a wall of boulders. There is a rare ore deposit behind this wall, but there are also three Electric Keese.
There is a wall of vines in the western part of the room. Cut them down to find a Hearty Truffle, then cut the next wall of vines and it will lead you down a hole with three Stalkoblins at the end.
In the room beyond the Stalkoblins, there is a wall of vines to the west with a treasure chest behind it that contains a Soldier's Shield.
Across from that, there is a ledge that you can use Ascend on. There is a Rock Like at the top of the tunnel. You can use Recall on its last rock to send it back to the Rock Like and break its armor. Then you can shoot its tongue to stun it, and hit its tongue while it is stunned until it is defeated. It drops a chest and a Like Like Stone.
Beyond the Rock Like, there is a rare ore deposit, some bomb flowers, and a wall of boulders. Break down the boulders and you will find a Shock Like. Dodge its electricity, then shoot its tongue to stun it, and defeat it as before.
After that, you can break down the wall of boulders that was behind the Shock Like and climb up into the tunnel to find one of Misko's treasures, the Rubber Armor.