This insular tribe dwells upon Mt. Gulg in Kholusia, its diminutive people rarely leaving the community of their birth. Dwarves are known for their skill at mining, metallurgy, and crafting mechanical marvels, but they themselves consider the true marks of dwarfhood to be respect for tradition and adherence to strict ancestral laws.
The largest island in Norvrandt, the greater part of Kholusia lies under the dominion of Eulmore, the city of final pleasures. Compared to other lands, it is known for experiencing few sin eater attacks, a reputation which draws throngs of refugees to its shores.
Sounds like it'll be a dwarven structure built into a cliff rather than any kind of barrier or a stopped flood if it's the place with the least amount of attacks.