Mount Doom, also known as Orodruin, and Amon Amarth was a volcano in Mordor where the One Ring was forged and destroyed in Sammath Naur, the Cracks of Doom, a fiery chasm within the mountain. It was the ultimate destination for Frodo's Quest of the Ring.
When Sauron chose the land of Mordor as his dwelling-place in the Second Age, Mount Doom was the reason for his choice. Having been originally a Maiar disciple of Aulë, the smith, he used the fire that welled there from the heart of the earth in his sorceries and his forging. The most famous result of his forging, and in fact the only one we know of for sure, was the One Ring.
Mount Doom was much more than just any volcano - Sauron seems to have extended his own power into it, just as his former master Melkor had extended his own power into the flesh of Arda as his means of corrupting the Valar's shaping of the world. In his case, it was probably due to his use of it as a foundry for the forging of the Ring, and was able to control its fires. It seems to have lain dormant when Sauron was away from Mordor, and sprung into life when his power grew.
With the destruction of the Ring, Mount Doom had a final, massive eruption, sending massive lava flows down all sides and scattering the area with volcanic debris. Several of the falling lava balls went flying at the Nazgûl as they tried to escape on their Fell Beasts, destroying the riders and their mounts.
Portrayal in Adaptations
The Return of the King filmIn Peter Jackson's trilogy of movies, the New Zealand volcano Mount Ngauruhoe was used as Mount Doom in some scenes. In long shots the mountain is either a large model or a CGI effect, or a combination. It was not permitted to film the summit of Ngauruhoe because it is sacred to the Māori of the region. However, some scenes on the slopes of Mount Doom were filmed on the actual slopes of Mount Ruapehu.
On November 22, 2012, it was incorrectly reported by media outside New Zealand that "Mount Doom" Ngauruhoe had erupted. The reported eruption was actually from nearby Mount Tongariro, not Mount Ngauruhoe.
Orodruin was Sindarin for 'Fire Mountain'. The literal Sindarin translation of Mount Doom was Amon Amarth, meaning 'Mountain of Fate'.
Forests & Mountains:
The rest of Arda: