Jutting out from a sheer cliff 1,430 meters high, the glass skywalk in Zhangjiajie National Forest Park makes mice of men.

"My girlfriend blamed me for not acting bravely," said a man from Shandong province, who refused to give his name because he was ashamed of not having the guts to walk across the see-through walkway.

"I will challenge the road next time, when I'm ready for the height, and then I will shout my name out loud."

The glass skywalk spans 60 meters of a 2-km loop encircling the vertical cliffs of Tianmen Mountain in Hunan province, a UNESCO World Heritage Site.

"Tourists can walk, run or even jump on the walkway as the fence and planks are all tempered glass," said Tian Huilin, deputy general manager at the tourism office of the Tianmen Mountain Scenic Spot.

Tian said the glass plank road is the first of its kind in the country and dwarfs urban skyscrapers for a higher and more distant view. 

"The experience is unique. Tourists can have a bird's-eye view of the rocky pinnacles rising from a coverlet of dense subtropical vegetation and sometimes veiled by clouds through glass, which will add thrills and fun for the tourists."

According to Tian, the project was inspired by the Grand Canyon Skywalk in the United States. The US counterpart is an observatory with a glass bottom to allow visitors to gaze into the gulf beneath their feet.

Li Aiping, a tourist from Hunan province, said the glass section of the walkway made her heart beat like a drum, but she enjoyed it.

"My mind went blank when I heard somebody walk beside me screaming," she said. "I probably won't dare to walk on it again."

Some people, however, are worried that a large number of tourists might jam the road.

"The idea is so cool. But if every tourist wanted to have a try, I'm sure people would have to wait in line for hours as I have seen in many other scenic spots," said Beijing resident Kang Wenxuan.

But environmentalists have criticized the glass skywalk, saying that the overhang will tarnish the pristine mountain.

"The glass road is odd compared with the ancient plank roads, which appear to be made of stone or wood and are more harmonious with the landscape," said Wang Yanyong, a tourism planning expert at Beijing Jiaotong University. 

He added that innovation should not go against the basic natural and cultural context.

In 2010, the number of tourists going to Zhangjiajie reached 24 million, up more than 24 percent year-on-year.