Casey gunned the machine, reveling in the strong purr of the engine. The initial need for speed had waned, and they now both rode in tandem, the darkness a deep unrelenting gloom broken only by the beams of light coming from their bikes. Given the light didn't give them much advance visual notice, she could only hope there weren't too many things to avoid. More than once she'd caught the glint of eyes and the scurry of a body as something hid.
At one point, she realized the tunnel had lightened. A gradually growing illumination, which turned out to be a vast chamber ringed in a narrow walkway that only allowed them to ride one at a time. He rode ahead of her, waggling the rear of his bike. Since she couldn't pass, she slowed a touch and glanced across the open space.
The waterfall, true to its name, poured but not in the way gravity usually worked. It flowed upwards, splashing into the ceiling before falling down.