Just above the Fairy Kingdom, surrounded by large boulders and rocks that work as a barrier. The trolls and goblins used to live in tunnels and caverns underground; when their territory is flooded, they build a floating city on the newly formed lake and rename the territory "The Great Troblin Lake". They are notorious for capturing "trespassers" and keeping them as slaves - in A Grimm Warning, the trolls & goblins are made to take a vow never to enslave anyone again.