The Fragment of the Shadow Realm was vast, its darkness drowning not only the surface of the dead god's sternum, but also swallowing a considerable stretch of the abominable jungle thriving in its hollow depths. The Dream Curse had lulled the Nightmare Creatures populating the area to sleep, so it was relatively safe.
Sunny and Nephis moved with sufficient speed, reaching the edges of the Fragment in a matter of hours. They could have been much faster, of course, but he used that time to teach her about the dangers of what lay beyond.