The Rehai Scenic Area, 10 kilometres south of Tengchong, is the most concentrated and accessible geothermal field in China. More than 80 hot springs occupy a landscape of mineral-stained vents, bubbling pools, and columns of steam rising from the ground. The centrepiece is the Dagunguo spring, where water boils continuously at the surface and the surrounding area is layered with mineral deposits in sulphurous yellows and silica whites.
The park is well laid out with boardwalks and paths connecting the main features. Beyond Dagunguo, a series of smaller springs of varying temperatures are scattered across the hillside, some accessible for soaking feet (if not more), and a wetland area in the lower section has its own quieter character. The steam and the geological violence of the landscape are the point — this is active geology visible at the surface, and the various pools, geysers, and mud pots each have distinct behaviour. Allow at least two hours.