About 30km drive from Hoa Binh will lead to a rest house named Kim Boi. The house was built near a large mineral water pool.

Visitors sitting inside the house can hear the sound of the water, which is at a constant temperature of 36ºC, continuously spouting out. Scientific tests have shown that the mineral water at Kim Boi is suitable to drink, bathe, and use in the treatment of rheumatism, intestinal diseases, stomachache, and high-blood pressure.

Kim Boi mineral water is bottled for drinking. It has almost the same composition as certain well-known foreign brands of mineral water.