Northern Mirkwood is a forested biome, above Mirkwood Corrupted and surrounding the Woodland Realm. It, unlike its southern counterpart, is mainly uncorrupted, and the forest is much less thick. No elves or structures spawn here, only vanilla animals, woodland elk, wild boars, black butterflies, and Mirkwood spiders during night. There is also no fog here, giving the forest up north much more visibility.