Black, as far as they could see. The sky covered in smoky clouds, around them an ocean of tar stretching boundless in every direction. Nothing else in the darkness between the two, not a sound or a trace of movement.
Twilight stood on the edge of the rock, the whole structure no larger than a house, the only stable ground in sight. For all they knew, it had been the top of a mountain at some point, and everything else had been covered by a flood. "What do you think happened here?" she asked.
"I can't tell you anything you can't already see for yourself," answered Celestia. "But whatever it was, I doubt it left much of a trace of what used to be here. If there was something, of course."
Twilight swallowed as she was reminded of what could have once been there, before whatever catastrophe had struck. "This could have been us," she whispered, mostly thinking aloud.
"But it wasn't." Celestia stepped to her side. "There's nothing we can do about it, Twilight. It's no use worrying over it."
"I know," Twilight replied. "That doesn't make it better." She turned, and began to walk around the rock's perimeter, studying the horizon. "Do you think we should explore the surroundings?"
Celestia softly bit her lip as she looked at Twilight. Not the worried, uncertain symptom of hesitation of someone who sees the benefits and risks of both paths. More like the petty pause of someone who does not want to be bothered, but knows it'll make them look bad. Still, the white alicorn was at least old and wise enough to provide a valid reason with which to mask her laziness. "I wouldn't risk it. There's nothing in sight, and that means both we're unlikely to find anything close, and we might not be able to get back here should we travel far enough to lose sight of this place."
Twilight had, unfortunately for Celestia, spent enough time with her to tell where her real motives lay. "Too bad Luna didn't come instead of you, right?" she playfully remarked, moving back towards the alicorn.
Celestia looked to the side, feigning the required amount of indignation over the perfectly legitimate yet still perceived as offence piece of critique. "Right," she quietly admitted. "But my sister is busy hunting."
"She is." Twilight stood at Celestia's side. "Well, we can always come back here at a later time. Prepared, now that we know what's in here." She looked at the other alicorn. "You can go back to your cakes now if you want."
Celestia's cheeks turned far more red than she would have ever allowed them to back in her ruling days. Which was still less than any normal pony's reaction, but nonetheless impressive on her. She just glared at Twilight, perfectly aware that she had nothing with which to fire back.
Twilight turned to leave. Then she turned again, as a deep, immensely loud wailing sound echoed towards them from the far horizon, like a violin note distorted and amplified to an impossibly degree.
And they both looked towards the distance, at the wall of blackness moving closer and closer, the wave rising from the dark ocean tall enough to reach the sky and swallowing everything in its path.