Ista, the fifth Weyr, is one of the most curiously constructed. Situated on the bay at the southwest corner of the Big Island, the black half volcano thrusts four fingers and a thumb into the tropical sky. The mountain must have been formed by an eruption that knocked the bay half of its caldera into the sea, letting lava flow in a gradual drop-off, which the pounding of the current has worn away into a plateau. For all its tiny size, Ista has a mind-boggling, mazelike warren of narrow tunnels that double back and run into one another.
Just offshore, a small mountain surfaces once in a while when there are earthshakes or upheavals. The beach under Ista Weyr is sand that, when inspected, proves to be black diamond dust.
Ista supplements the lack of dragonrider weyrs with "forest weyrs," cliffside dwellings on the outer face of the Bowl. It attained its full population shortly before the Second Pass in the year 258. Fresh water flows into the caverns from the northeast through underground streams. The corral where the herdbeasts graze has an artificial pool filled from pipes coming through the Weyr. With the sea so near at hand, there is no need for a bathing pool for dragons, though the dragonets who have not yet learned to fly like to bathe under the cataract of the artificial waterfall created by Ista Weyr's architects in the north wall of the Bowl.
— Jody Lynn Nye with Anne McCaffrey, The Dragonlover's Guide to Pern, 2nd ed. (New York: Ballantine Books, 1997), 147-148.