Windy Valley|ウィンディーバレー|U~indībarē}} is one of the action stages featured in Sonic Adventure.
A large set of greenery ruins set flying high in the clouds amongst dangerous gusts of wind and a lethally violent tornado, Windy Valley is located inside a cave within the Mystic Ruins. The level is split into three main parts: the windy hills at the beginning, the tornado, and the aerial spiraling tracks. Sonic goes through all three, while Tails goes through only the third, and Gamma goes through only the first. Windy Valley was the only level that went through the biggest visual changes between the announcement of the game on August 22nd, 1998 and its release in December. Though still broken up into three parts, the layout and textures for each were completely redone. The prototype images can be viewed below.
Windy Valley is Tails's first level, where he must race Sonic to the Chaos Emerald at the end. Interestingly, because the whole level moves downward, Tails can fly from the beginning to the end of the level without touching the ground.
Windy Valley is Gamma's third level. Here, Gamma searches for E-103 Delta to free him after being banished from the Egg Carrier. Like his other levels, enemies and other structures must be destroyed to increase the time limit.
- Windy Valley appears in the Sonic the Hedgehog comic spin-off, Sonic Universe, as a location that three of the Secret Freedom Fighters–Silver the Hedgehog, Larry Lynx, and Shard the Metal Sonic–go to while spying on Geoffrey St. John right before the Ixis Resurgence. (SU #41, #43)
- In the Sonic X episode "A Chaotic Day", Sonic and Tails head to what appears to be Windy Valley in search of a Chaos Emerald.
- The music in the Windy Hills section of Windy Valley is based on the Special Stage music from the Mega Drive version of Sonic 3D Blast. The aerial tracks area has music based on Green Grove Zone Act 1 from the same game.
- Windy Valley became the location of the Dream Discus event in Mario & Sonic at the London 2012 Olympic Games.
- A segment of Windy Valley, called Windy Hill, is also the same name as a stage from Sonic Lost World.