Dan McCoy provides all the ins and outs of the Norse afterlife in this interesting article. I was interested to read what he thinks are connections between myths of journeys to the underworld and shamanic journeys described by other northern peoples.
What the sources do describe in uncharacteristic detail, however, is the course that one had to travel in order to reach Hel. Given how precisely they correspond to the narratives of traditional shamanic journeys of other circumpolar peoples, they seem to recount, and possibly provide templates for, the journeys of Norse shamans. Throughout Old Norse literature, we find instances of such journeys to the underworld undertaken by gods or humans in order to recover a dead spirit or obtain knowledge from the dead.
Hel was located underground – down and to the north, the realm of cold and general lifelessness. It was reached by descending from a higher point with the help of a guide – an unnamed (dead) woman in Hadding’s case, and Sleipnir in the Prose Edda and the poem Baldrs Draumar (Baldr’s Dreams) in the Poetic Edda. After traveling through darkness and mist, one would come to a river, perhaps a torrential river of water, but more commonly a river of clanging weapons. There was a bridge over the river that one had to cross. After a time, one would finally arrive at the wall surrounding Hel, but, for reasons we don’t entirely understand, it wasn’t thought wise to attempt to enter through the gate. More surreptitious ways were preferred. At that point, one would be, in spirit, in the world of the dead in their graves, and one had to take extreme precaution to ensure that one didn’t become trapped there while accomplishing one’s purpose, which is surely part of the reason why all of the surviving accounts of such journeys from northern Europe involve quests undertaken by gods, heroes, or other specialists rather than ordinary people.