Fire river

WHEN THEY REACHED THE LEDGE, Annabeth was sure she’d signed their death warrants.
The cliff dropped more than eighty feet. At the bottom stretched a nightmarish version of the Grand Canyon: a river of fire cutting a path through a jagged obsidian crevasse, the glowing red current casting horrible shadows across the cliff faces.
Even from the top of the canyon, the heat was intense. The chill of the River Cocytus hadn’t left Annabeth’s bones, but now her face felt raw and sunburned.
Assuming they could make it down to the fiery river, which she doubted, her plan seemed certifiably insane.
A few steps below her, Percy grunted as he reached for another handhold. “So...what is this fire river called?”
“The Phlegethon,”





An entire phalanx of Cyclopes charged forward, knocking smaller monsters out of the way.
Annabeth figured she was about to die. “It had to be Cyclopes,” she grumbled.
Percy gave a battle cry. At the Cyclopes’ feet, a red vein in the ground burst open, spraying the monsters with liquid fire from the Phlegethon. The firewater might have healed mortals, but it didn’t do the Cyclopes any favors. They combusted in a tidal wave of heat. The burst vein sealed itself, but nothing remained of the monsters except a row of scorch marks.

HoH ch.7/69