Whim Balloon (Indoor)

Inside Waterfall Cavern (Firework Isles). After defeating the first few Esselings, there’s a fork. Keep left to find this balloon. You can also reach it later on.

Inside Songbreeze Cavern. Take the left exit at the endpoint (after turning around).

Inside Gloomy Cavern. Towards the right side near the beginning. Jump across the alcove where two Spear Sacks are. Use a plunging attack to break the wooden floorboards, then defeat the Esselings down below.

Inside Behind-the-Mountain Cavern. When you enter the tall area with a lake, jump across the water. Use a plunging attack to break the glowing crate, then chase the balloon.