Rafts

The expedition travels a great deal of time on rafts on a river under the earth's surface. These rafts are later stolen by Walker and Shoat when they abandon the scientists after Cache III.

Lights

While at the trading center, Ike shows Ali a bunch of oil lamps that he found hidden in a room at the top of the center. Later, Ike uses this oil to light the entire structure on fire to escape from the attacking hadals.

Hadal Tattoos

It is customary for the hadals to cover their bodies and the bodies of their captives in tattoos. When Ike is rescued, his face, arms, and torso are covered with tattoos that make it difficult for him to hide his experience as a captive.

Ali's Maps

During the expedition, Ali draws maps of the expedition's course and everything they see. When the scientists are marooned by...