He starts by going in to a cave under the Gnipahellir (a protruding cliff high on a mountain in Jotunheim). He sneaks past Garm, the fiendish hound that is chained in the cave to guard it. From the cave he follows a tunnel down to Niflheim, then the Hel road through Niflehim to Helheim (the second layer of Niflheim). To get from one level to the next, he must cross the Gjallarbru ("Resounding Bridge"). When a living creature crosses the bridge, even the lightest footsteps sound like thunderclaps, alerting all the dragons and undead of both levels are made aware ot its presence. There's also a giant maiden, Mòdgud, guarding the bridge. The final obstacle is getting past the gates of Hel, into her personal domain.
