Baiheliang is a natural ridge of sandstone in the Yangtze off Fuling, and it is invisible for most of the time: it lies below the surface except in years of exceptional drought, when it emerges as a long, low spine of rock in the middle of the river. Because its appearance was itself a signal - a marker of how severe the dry season had been - people carved it. For twelve centuries, from the Tang dynasty onwards, officials and scholars who saw the ridge exposed recorded the year, the date and the level of the water on the rock, and the result is the longest continuous series of low-water observations anywhere in the world.
What is carved on it
The ridge carries more than a hundred and sixty inscriptions in a range of calligraphic styles, a number of poems, and a set of stone fish carved at intervals, which served as the actual gauge: when the water fell to a particular fish, that was the measure. The earliest dated inscriptions are from the eighth century. Taken together the carvings are a record of hydrology, of calligraphy and of the people who worked on the river - a document as much as an artwork.
Why there is a museum
When the Three Gorges reservoir filled, the river level at Fuling rose by some forty metres and Baiheliang disappeared for good. Rather than lose the site, a protective structure was built around the ridge itself - a chamber on the river bed, closed over the carvings and filled with filtered water - and visitors descend through a long tunnel to a gallery with viewing windows, where the original carving is visible under water, lit and legible. The Baiheliang underwater museum opened in 2009 and is the first of its kind in China.
Practical notes
Fuling is about forty minutes from Chongqing by high-speed rail, and the museum is a short taxi ride from the station, which makes this an easy half-day from the city. Numbers are limited and timed, so book ahead, particularly at weekends and in the Chinese holidays. Photography inside the gallery is restricted, the tunnel is cool, and the exhibits upstairs explain the hydrology and the calligraphy for anyone who does not read Chinese well enough to follow the inscriptions themselves.
