The eighth and final level is known as the Deep. It remains constantly underwater at all times.
There is an old cautionary tale told only in inns on the level above, telling of would-be explorers who once attempted to reach the bottom of the Deep, but who fell afoul of legendary water-dwelling beasts who dwell in those dark depths. There are confirmed sightings of strange creatures that surface only to attack boats and swimmers before disappearing again.
Nolthrir will often attempt to swim as far down into the Deep as they can, as part of their traditions.