The hot spring at Rainbow Resort comes from 1460m below the ground. The waters are therefore better and purer than other nearby hot springs just a few hundred meters down. To keep the hot spring's bore hole clear, each week the resort opens the valves for geothermal well beside the open-air baths in the early morning or afternoon. The hot spring waters and steam fountains into the air, creating shimmering rainbows across the sky. This became known as the "Rainbow Spring" and is an attraction unique to the Jhihben hot spring district.