Silence hangs over the final circle, where the rivers of Hell empty into a frozen lake. Here, the worst sinners are immobilized in icy oubliettes, thousands of heads sticking out with blue faces & clacking teeth. There are four concentric rings of sinners, distinguished only by the position of the heads. In the first, Caina (named for the first murderer & holding sinners who betrayed relatives, naturally), heads face down. In the second, Antenora (betrayers of their homelands, after a Trojan turncoat), eyes look forward. All the while, gravity grows stronger as we near the Earth's center.