Brightcap Cave is to the east of Rito Village, near Oromuwak Shrine.
Cave Location
Brightcap Cave is at -3001, 1640, 0201, just east of Oromuwak Shrine, which is east of Rito Village.
Cave Features
There are two ore deposits near the entrance of the cave. Farther in, the cave slopes downward and is lined with Brightcaps. You will find a bomb flower in a small tunnel, after which you encounter a Horriblin. Beyond that, there is a Like Like.
In the area beyond that, there is a ledge surrounded by brambles, but if you continue going clockwise on the lower level, you find one of Misko's treasures blocked by a wall of brambles. Burn the brambles and open the chest to get the Frostbite Shirt.
You can use Ascend on the ledge surrounded by brambles to reach the cave's Bubbulfrog and some luminous ore deposits.