Mirkwood was truly a scary, forbidding, creepy, gloomy place with huge trees and super dense foliage needing serious trimming above, while strange unknown critters nosed about in the undergrowth and thick leave piles. There were black squirrels abound too. Cobwebs seemed copious and super-strength industrial grade. Air quality was nothing to shout about either depressing even the Dwarves with its stuffy stillness.
After Rivendell, the journey across the Misties to get to the Wilderland on the side was a difficult itinerary to handle unless one has a deeply experienced guide in tow. It was full of winding twists and and deceptive pathways.