What in the Hell

Jynn scooted closer and closer to the north, curious to see the harshness of the winter there despite her more sensible side urging her to wait til spring. She would have continued due north if it hadn't been for an odd opening in the ground. Curiosity drove her forward and down into the depths of the strange cave. One of the first things she noticed was that it seemed much warmer down here and up ahead was a strange glow. Did someone live here? Her ears flicked forward but she couldn't quite describe what she was hearing. It sounded almost like a low wind and cracking rock. As she rounded the corner she froze in shock as she saw a river of lava eating its way through the cavern.

The lava was dark but full of brilliant yellow and orange cracks as it rolled along. Columns of rock supported the roof of the cave but here and there she saw falls of lava, of all sizes, oozing down into the main river. Sparks flew into the air and it was positively sweltering. A v-like crack in the rock wall ahead of her revealed more lava falls dripping down into another flow. How vast was this place?