The Diamondback Mountains run the central spine of Apketrii, their ridgeline sinuous and regular enough to give the range its name—viewed from the coast, the successive crests resemble the segmented pattern of a serpent's back. The rock is hard basalt with minimal forest cover above the lower slopes, and the ridgeline stays visible from most points on the island.
Keletus quarries the Diamondback foothills for building stone, shipping dressed blocks through valley roads to the coastal shipyards. The mountains offer little else beyond terrain: no significant ore, no passes that improve on the coastal routes. Keletus military candidates have trained on the upper ridgelines for generations, and the hardest ascents have names.