The Forinthry dungeon was introduced to RuneScape when the Wilderness and free trade was brought back. The dungeon is primarily home to the revenants that used to roam the Wildereness, and is a very dangerous place. There are two entrances to the dungeon, one being in level 17 Wilderness near the south-west steps of the Wilderness volcano, and the other at level 31 Wilderness east of the Forgotten cemetery. The monsters inside of the dungeon are Ankou, Lesser demons, Green dragons, Greater demons, Hellhounds, and all levels of Revenants. These Revenants are now the only monsters to drop the various unique pieces of equipment (Corrupt dragon, Morrigan's, Zuriel's, Vesta's, and Statius's), Brawling Gloves and Statuettes, which were previously obtained as a random drop from killing other players.

The dungeon is a very dangerous place; it is part of the Wilderness itself, meaning other players can attack you inside, and further it is not recommended to enter without a Forinthry bracelet as it will cause the revenants to be un-aggressive for an hour, and not take damage for up to a minute. In addition, the dungeon is multi-combat, meaning that multiple people and monsters can attack you if you enter it. No quests take place in the dungeon.

Ankou (Level 75) Green dragon (Level 79) Lesser demon (Level 82) Greater demon (Level 92) Hellhound (Level 122) Revenants (Levels 7-135)