Bolotnyk is a malevolent spirit-lord of swamps in Slavic mythology. He is a relative of the Lisovyk and Vodyanyk. It was believed that the Bolotnyk was a motionless fat creature that had no eyes and sat at the bottom of the swamp, covered in mud, algae, snails, and fish scales. According to other sources, he had the appearance of a naked gray-haired old man covered in gray hair and algae, with long frog-like hands, bulging eyes on a wide yellow face, a curled tail, and a long beard from which mud dripped. According to some beliefs, the Bolotnyk lived in a large stone house at the bottom of the swamp. However, his place of residence was the entire swamp. And his favorite places were quagmires, holes, and pits.
The main occupation of the Bolotnyk was to lure people into the quagmire. It was believed that it was easiest for him to do this with a person who played the flute at night. For this, he could laugh, roar, groan, or reproduce animal and bird sounds. Although he could also simply frighten with sharp sounds, sighing, bubbling, loud smacking, splashing in the water. He also created so-called charms - places on the swamp that look like flowering meadows, but in fact are just a weaving of marsh grass on the surface of the water.