The jungle, which once spread across almost all of Riven before it broke up into separate islands, was systematically deforested by Gehn until only a small portion of it remained. Inside was the wahrk totem and the island's firemarble dome. Bordering the jungle on the lake side, near the firemarble dome, was a deep fissure which exposed an underground magma chamber; an illustration of how fragile and unstable the Age was. A large swath of clear-cut trees was located on the highest part of the island, and a logging cart connected Jungle Island with nearby Book Assembly Island, where the trees were chipped, pulped, and turned into paper for use in new Books.
The lake was a deep depression which connected to the sea, and was surrounded by a high cliff wall. It was also the hub of native activity on the island. The Rivenese village sat high on the cliff overlooking the lake, and a variety of other structures were arrayed around its perimeter. Gehn's wahrk gallows sat directly across the lake from the village, where everyone could see Gehn's victims be fed to his pet wahrk for their crimes. Gehn would observe these executions from a control chair high above the lake, where he could operate the gallows's iris and show clemency toward the accused. Prior to their execution, prisoners were held in a small cell in the cliff side. The Moiety had built a secret tunnel behind one of the walls of this cell, and could escape through it back to Tay. In another corner sat the schoolhouse, where the Age's children were taught how to read, write, and speak D'ni.
In the center of the lake was a small spit of rock, on which Gehn built a periscope. It was able to swivel 360 degrees, and was connected to a viewing device on Survey Island. Through this, Gehn could keep a watchful eye on his subjects without needing to be seen doing so.
A small submersible which drove along the lake bed on rails connected these various locations. The unique heat-phobic properties of Riven's water created columns of open air where heat from an underground magma chamber rose up to the surface. These columns served as egress points for the submersible, where its driver could get out without getting wet.
On the shore of Jungle Island, just on the other side of the cliff from the village, was a small lagoon. Sunners would often come to bask on its broad, flat rocks, giving the place its name. A narrow staircase cut through the rock connected the lagoon to the jungle, as well as the maglev station on the far side of the island.