Lonely Island
From Grimhaven Wiki
Lonely Island is a custom map. Located far south of the Desert.
You can access it by entering Thais depot and go down a floor there you will find a teleport.
Creatures that can be found here:
Deepling Brawler, Deepling Scout, Deepling Spellsinger, Deepling Guard, Deepling Elite, Deepling Tyrant, Wyrm, Elder Wyrm. Nightmare.
For more information about where check out Spawns.