Twentyone Mile Creek begins its long and steep journey from Rainbow Lake, high up and between Mount Sproatt and Rainbow Mountain.  Cutting between the two mountains, Twentyone Mile Creek flattens out somewhat, passes under Alta Lake Road, then winds its way through a deep and dark forest before flowing into the River of Golden Dreams near the end of Lorimer Road.  This hidden forest extends from Rainbow Park to Emerald Forest and between Alta Lake Road and the River of Golden Dreams.

Emerald Forest is a cute little forest that is well hidden between Whistler Cay and Alpine.  From Whistler Village, if you go down to the end of Lorimer Road you will see the Valley Trail branch off in three directions.  If you take the direction toward Meadow Park, you will immediately cross the bridge over the River of Golden Dreams.  The paved trail then continues to Meadow Park, but if you take the first left after crossing the train tracks, you will come to the old gravel pit and the start of the Emerald Forest trails.