From WoWWiki

Fallen Sky Lake is located in Ashenvale south of Silverwing Outpost, west of the Warsong Labor Camp, and northeast of Silverwing Grove. It is a small lake, and the island in the center in it holds a level 30 Shadethicket Oracle that you must kill for a quest. Surrounding the lake are other shadethickets of lower levels than the oracle.

Subzones of Ashenvale

Astranaar • Bathran's Haunt • Bloodtooth Camp • Bough Shadow • Demon Fall Canyon • Demon Fall Ridge • The Dor'Danil Barrow Den • Falfarren River • Fallen Sky Lake • Felfire Hill • Fire Scar Shrine • Forest Song • Greenpaw Village • The Howling Vale • Iris Lake • Kargathia Keep • Lake Falathim • Maestra's Post • Moonwell • Mor'shan Rampart • Mystral Lake • Night Run • Nightsong Woods • Raynewood Retreat • The Ruins of Ordil'Aran • The Ruins of Stardust • Satyrnaar • The Shady Nook • The Shrine of Aessina • Silverwind Refuge • Silverwing Grove • Silverwing Outpost • Southfury River • Splintertree Post • The Talondeep Path • Thistlefur Hold • Thistlefur Village • Warsong Labor Camp • Warsong Lumber Camp • Xavian • Zoram'gar Outpost • The Zoram Strand