The ground drops away without warning. At Qingkou, in the hills of Wulong in the south of Chongqing, the forest opens onto a hole in the earth so large that you can hardly believe it: a giant doline, or sinkhole, hundreds of metres across and deep enough to swallow a skyscraper. Karst country is full of such things, because limestone dissolves in rainwater, and over millions of years, caves and tunnels have collapsed to create these enormous pits.
Wulong is part of the South China Karst, a UNESCO World Heritage Site first listed in 2007 and extended in 2014. It is one of the finest karst landscapes in the world, a region of natural bridges, canyons, caves and sinkholes, set in steep, forested hills. Nearby, the Three Natural Bridges, huge stone arches spanning a river gorge, have been used as a film location, and the Furong Cave is a vast cavern with underground rivers and strange formations. The scale of everything is hard to describe.
The surrounding country is green and damp, with terraced farms, villages of grey brick and tile, and mist that clings to the valleys. Maize, tobacco and vegetables are grown on every available patch of flat ground, and local farmers have a hard, steady life. The climate is humid subtropical, with hot summers and mild winters. Spring and autumn are the best seasons to visit, when the air is clear and the forest is bright.
For riders, the roads here are well built but twisty, climbing and dropping through the hills with many bends, tunnels and viaducts. Rain and fog reduce visibility, and trucks and minibuses use the same lanes. Honestly, foreign motorcycle travel in China requires special permits and local registration, and most visitors arrive by bus or hired car from Chongqing. If you are able to ride, plan fuel carefully, because stations in the mountains can be far apart, and fill up in larger towns such as Wulong county seat. Food is Sichuan-style and spicy, and local guesthouses offer simple rooms. Allow plenty of time for the paths down to the doline, and wear shoes with good grip.