Chudo-Yudo (#152)
In Greek mythology, after dying, people travel to the underworld called Hades and have to cross the river Styx with the help of the ferryman Charon. (Remember the other two rivers in Hades, from fact #116?)
Ancient Slavic mythology has a similar understanding of the dead's journey but they spice it up a little and add: a dragon. Also, they're not getting any help from ferrymen.
In the the Ancient Slavic underworld, the river situation is a bit more complicated than in Greek mythology: There's the river Smorodina, which smells really, really bad. Also, the river is on fire. Like literally, burning with fire.
Good thing is, you can see and smell it from afar. Also, there's a bridge. Bad thing, the bridge is protected by a giant dragon called Chudo-Yudo. Which, by the way, is the pet of Baba Jaga from fact #136, remember?
I'd like to call it a "hell of a journey", but that wouldn't be correct, because Ancient Slavs didn't really think about it like that. Their underworld is just a place, where the soul of a deceased went before it eventually came back to earth.
https://www.rbth.com/history/327737-ancient-slav-underworld-death-religion