The Yellow River (Huang He) is China’s second longest stretch of water and it’s probably the muddiest river in the world. Over a billion tonnes of silt and sediment flow through it each year, giving the Huang He its distinctive yellow color and making it a poor choice for washing your socks in.
Although the Great DA-YU took care of the Great Flood, the Yellow River was still prone to flooding. So an enthusiastic mortal named Fengyi (also known as Pingyi) tied heavy rocks to his back and jumped into the water as a supreme sacrifice.
For his pains he was granted immortality and promoted to God of the Yellow River.
Following his example, it became the custom to throw a young virgin into the river on the anniversary of his death. This practice appears to have died out.
Incidentally, his sister is the Moon Goddess CHANG-E. Godliness must run in the family.