What forest do the dwarves cross?

The dwarves cross Mirkwood, the vast forest that lies east of the Misty Mountains. In The Hobbit, the company enters this dangerous woodland while travelling toward the Lonely Mountain and Erebor.

Mirkwood is not simply an ordinary forest. Tolkien describes it as a dark and perilous region filled with giant spiders, confusing paths, and enchanted waters. Gandalf leaves the company before the crossing, so Bilbo and the dwarves must find their way through without his guidance. Bilbo proves especially important when he rescues the dwarves from the spiders using his sword, Sting.

The forest is also home to the Woodland Realm, ruled by Thranduil. The dwarves are captured by the Wood-elves after Thorin refuses to reveal the purpose of their journey. Bilbo, made invisible by the One Ring, remains free and eventually helps the company escape in barrels down the Forest River.

Readers sometimes confuse Mirkwood with Fangorn or Lothlórien, both important forests elsewhere in Tolkien's legendarium. The Old Forest belongs to the world around the Shire and is not part of the route to Erebor.