The Rotten Vale is a massive area covered in the rotting bones of Elder Dragons and other monsters that have come there to die. It sits at the bottom of the Coral Highlands, though perhaps it is more accurate to say the Coral Highlands grows from the Rotten Vale.
The Rotten Vale can be divided into three sections; the third being much smaller in size.
The upper area near the starting camp is fairly open and mostly inhabited by Radobaan, Hornetaur, and Vespoid. It is mostly made up of large bony structures.
The area that can be reached by jumping from the upper section has numerous Girros. Of course, their leader Great Girros lives here, while Odogaron and Radobaan can also be found in the upper and deeper portions of this zone, respectively. In addition, the second camp is located in this section. Effluvium is a big problem from the first portions to the deepest parts of this section. The corpses of Raphinos and, very rarely, Legiana will occasionally fall to this area.
The depths of the Rotten Vale has acid that can damage hunters. The dens of Odogaron and Vaal Hazak can be found here.
Small Monsters - Boaboa, Gajalaka, Girros, Grimalkyne, Hornetaur, Mosswine, Raphinos, Vespoid
Native Large Monsters - Acidic Glavenus, Great Girros, Rajang, Furious Rajang, Odogaron, Radobaan, Tigrex, Vaal Hazak, Blackveil Vaal Hazak
Invasive Large Monsters - Banbaro, Bazelgeuse, Deviljho, Savage Deviljho, Fulgur Anjanath, Ruiner Nergigante, Ebony Odogaron, Velkhana