Finally they arrive at the end of the tunnel - which they might notice a bit ahead of time, as Mary Ann's torch hits something at the end of the tunnel.

There's no wide empty space here, but instead... a wall covered in giant brown fur. A wall that is moving very slowly in synch with the breeze. Approaching it will show that it is rather some giant furry creature (at least going by the size of the fur) resting in a presumably equally giant cave. There's enough distance between the cave walls and the fur wall to walk in between, which only underlines how big everything must be.