Train K7039 carries about 1,000 passengers from Harbin, capital city of Northeast China's Heilongjiang province, to Mohe, China's northernmost city, on a daily basis.

"The lowest temperature outside the train coach hits around -40 C. It's very common for the train to run in heavy snow," said Chai Xiulin, a train attendant.

"If that's the case, we have to clean the snow at the gaps of the train doors about 15 times each trip," said Chai.

Despite the extreme cold weather, more tourists have chosen the province as their travel destination.

Passengers spend nearly 14 hours on the 1,194-kilometer rail line, which is also a great challenge to the train workers, who must keep the coaches warm.

Thanks to the extreme chill, the train doors easily become frozen.

"Every half-hour, we pour hot water into the toilet drains to prevent them from being frozen," said Chai. "We also adjust the air conditioner to keep a warm temperature."

"We feel warm in the coach even without a coat on," said a tourist from Fujian province in East China. "I believe it will be a great trip to Mohe."

"As a train worker, I feel quite honored to provide all the passengers a comfortable trip on the train," said Chai.