In August 2016, with the help of travel agencies from both sides of the border, Hou set out from Jeminay, a Chinese county bordering Kazakhstan. It took him 33 days to paddle the 1,500-km section.

The journey was longer and tougher than he expected.

The river width and current varied constantly. He fought hard to meet his target of 50 km a day. Camping on the riverbank when dusk fell was risky.

"I was lucky to return from the dangerous journey unharmed," he said.

Along the way, Hou was deeply moved by the friendly Kazakh people who gave him fresh produce and invited him to stay at their homes.

It has not been cheap. The challenge has cost a good portion of his savings.

To finish the task, he has to kayak further than the total of his two previous trips.

He also has to cross the vast and frigid Siberian landscape. The adventure in Russia will be much more demanding - physically and financially.

Hou went to Russia in September to assess his travel route and to coordinate with local tourism authorities.

He said the preparation is going well. The prospect of navigating a watercourse that is frozen solid for much of the year has not dampened his ambition.

Hou plans to start from the Russian city of Omsk next summer and to paddle all the way to Labytnangi, the last town on the Irtysh. From there he will approach the great northern ocean.

"I want to be a true hero in the eyes of my daughter," said Huo, who has a 12-year-old girl. Hou's wife, who at first did not understand his drive to complete such a dangerous journey now accepts his ambition and backs him.

"That support inspires me to hold on to my dream, no matter how many challenges I encounter," he said.