Non-canon warning: This article or section contains non-canonical information that is not considered to be an official part of the Legend of Zelda series and should not be considered part of the overall storyline.
The Portal of Doom is an object from the non-canonical book Link and the Portal of Doom. A mysterious portal, it appears in Hyrule years after the events of The Legend of Zelda: Ocarina of Time.
The Portal of Doom appears in a wall near Kakariko Village. Link discovers it and finds that Cuccos and other objects are being sucked into its vortex, leading him to realize that he has no choice but to stop it. He finds a map next to the portal, which reveals that he has to learn parts of an ancient song from various locations across Hyrule to seal the portal.
Navi believes that the Portal of Doom leads to an alternate dimension, and Link surmises that it must be an unpleasant dimension, judging by the chill he felt when he almost got sucked inside it.
The Portal of Doom is eventually sealed by Link, after he learns the ancient song.
Non-canon warning: Non-canonical information ends here.