The Deserted Island is the 'quest' version of Moga Woods. Tall cliffs surround this ancient forest as hints of an ancient civilization wink through trees and walls. A mix of open land and huge underwater zones, the Deserted Island is the most expansive and clutter free area in Monster Hunter 3 Ultimate, outside of the arenas.
Aptonoth, Bnahabra, Altaroth, Kelbi, Ludroth, Epioth, Jaggi, Jaggia
There's nothing particularly special to know about the Deserted Island. You don't need any items to help you survive, so it's a good idea to unload your pack of any hot/cold drinks you might be carrying to free up space for more traps, bombs, barrels and the like.
In fact the best thing about the Deserted Island is that herbs, mushrooms and honey are everywhere so whipping up a new potion in a pinch is never an issue.
Shortcuts & Secrets
Base Camp to Area 9: From the base camp leap into the water and swim straight forward. Slightly under the water you'll see an opening, swim through it and you'll be in Area 9.
Veggie Elder: When you enter Area 4 from the south you'll drop into the cave. Along the wall to your right is a crawl space, enter it to find a small Felyne camp; the Veggie Elder is here when not at Base Camp