Mount Doom is the mountain where the One Ring is destroyed in J.R.R. Tolkien’s The Lord of the Rings.
Mount Doom, also called Orodruin in Tolkien’s invented Sindarin language, lies in Mordor. Sauron originally forged the One Ring in its fires, and the Ring can be unmade only in the same volcanic fire where it was created.
Frodo and Sam reach the mountain after crossing Mordor with Gollum’s help. At the Cracks of Doom, Frodo claims the Ring rather than willingly destroying it. Gollum attacks him, bites off his finger, and falls into the fire while holding the Ring, completing its destruction.
Mount Doom is not the same mountain as Caradhras, which the Fellowship tries to cross near Moria. Nor is it Barad-dûr, Sauron’s fortress. The mountain’s destruction causes the collapse of Sauron’s power and the downfall of his realm.