Underground River Tunnels

Going back in time to the point that Scaly jumped into the hole in the middle of the alleyway to escape from the humans chasing after her, she found herself landing on a few mossy stone bricks that seemed to have deteriorated to the point that it was falling apart.

Looking around herself to make sure it wasn't a dead end that she had ended up jumping into, Scaly was relieved to discover that she was inside a rather large underground tunnel connected to three other underground tunnels. All made out of stone bricks that seemed to have deteriorated enough for her to worry about the ceiling of the tunnel suddenly caving in on her.

Not just that, but she also discovered that there seemed to be some kind of river running through the strange stone brick tunnels, taking up most of the space inside of them, while only leaving behind a small space for walking.