Standing at over 18,000 ft, Arddachwyr is the second tallest mountain on Gylidd island. Named for the Gylidder term for "Thunder Mountain," this peak is tall, curves to the south and gains altitude much more aggressively than the other mountains in the Northern Rachis Range. Its title comes from the sounds of wrought iron and industry that bounce up and off the mountain from Hangorfeydd. On a clear day, the thunderstorm-like noises can be heard from as far away as Orlewynd.