Van mentioned it the way he mentions things he considers obvious: d'divi has three tails. The three rivers draining The Dark Peak — the Dun, the Loxley, the Rivelin — are not waterways; they are the three tails of the divine serpent, and this is the first thing you learn here and the last thing you remember. Dunlockslyn is not violent, which is not the same as safe: the hazard is that the journey ends at the Ripperthroat mountains, and it ends once. Every denizen in The Dark Peak, regardless of species, eventually takes the dunfall. During a rockcrust episode in S6, Van spoke to it directly — "Oh Dunlockslyn. I am ready for you. I am primitive again" — and the god apparently judged him unready, because he is still here.