Isle of Berk, aka Eostera, is the island where "The Apex" fought "The Apex Rathalos", specifically in the Volcano zone (named "Battle ground" in the image). This island was originally very dense and compact. But, the clash of the god-like The Apex with the titanic Apex Rathalos cracked the island into several parts. This island is now considered forbidden, since it has naturally become where all monsters live. Only the Zen Knights are allowed to enter this island.