Tartarus jump

Annabeth wanted to curl up next to Percy and go to sleep. She wanted to shut her eyes, hope all of this was just a bad dream, and wake up to find herself back on the Argo II, safe with her friends (well...as safe as a demigod can ever be).
But, no. They were really in Tartarus. At their feet, the River Cocytus roared past, a flood of liquid wretchedness. The sulfurous air stung Annabeth’s lungs and prickled her skin. When she looked at her arms, she saw they were already covered with an angry rash. She tried to sit up and gasped in pain.
The beach wasn’t sand. They were sitting on a field of jagged black-glass chips, some of which were now embedded in Annabeth’s palms.
So the air was acid. The water was misery. The ground was broken glass. Everything here was designed to hurt and kill.

Of course if they stayed here, they would die anyway. Blisters had started to form on their arms from exposure to the Tartarus air. The whole environment was about as healthy as a nuclear blast zone.

I know.” His voice sounded as brittle as ice. “They’re telling me the same stuff. I think...I think this moat must be the border of Night’s territory. If we get across, we should be okay. We’ll have to jump.”
“You said it was twenty feet!” “Yeah. You’ ll have to trust me. Put your arms around my neck and hang on.” “How can you possibly—”
“There!” cried a voice behind them. “Kill the ungrateful tourists!” The children of Nyx had found them. Annabeth wrapped her arms around Percy’s neck. “Go!” With her eyes closed, she could only guess how he managed it. Maybe he used the force of the river somehow. Maybe he was just scared out of his mind and charged with adrenaline. Percy leaped with more strength than she would have thought possible. They sailed through the air as the river churned and wailed below them, splashing Annabeth’s bare ankles with stinging brine.
Then— CLUMP. They were on solid ground again.
“You can open your eyes,” Percy said, breathing hard. “But you won’t like what you see.” Annabeth blinked. After the darkness of Nyx, even the dim
She realized she’d forgotten all about their pursuers. “What happened to Nyx...?” She turned. Somehow they’d landed several hundred yards from the banks of Acheron, which flowed through a channel cut into black volcanic hills. Beyond that was nothing but darkness.
No sign of anyone coming after them. Apparently even the minions of Night didn’t like to cross the Acheron.
She was about to ask Percy how he had jumped so far when she heard the skittering of a rockslide in the hills to their left. She drew her drakon-bone sword. Percy raised Riptide.

HoH ch.6, 56