A 28-year-old British explorer has become the first person to complete a 4,000-mile (6,437km) trek along the Yangtze River in China.

Ash Dykes, from Old Colwyn in north Wales, finished the year-long expedition on Monday, overcoming blizzards, a landslide and temperatures as low as -20C (-4F).

Dykes was cheered on by British family and friends as well as Chinese supporters as he crossed the finish line to become the first person to walk the third longest river in the world.

“It feels amazing. It hasn’t kicked in yet,” Dykes said, adding that the trip took two years to plan and one year to execute.

Ash Dykes said he took note of the plastic and pollution from the source of the Yangtze river to the sea. Photograph: PR

He said the greatest challenge was reaching the source of the river, which at 5,100 metres is almost the same height as Mount Everest base camp. “There were worries I wouldn’t get to the source,” he said, adding that it was a lot harder than he had anticipated. Four members of his team left the expedition before it began due to altitude sickness.

Dykes said that early in the journey he was followed for two days by a pack of wolves who had recently killed a woman. “We could hear them howling and we felt super vulnerable of course. We had to stay vigilant. There were moments when I thought what on earth have I put myself through for the past year,” he said.

The expedition is Dykes’ third world first. In 2014, he became the first person to walk across Mongolia from west to east in an unsupported solo expedition that took 78 days. He also became the first person to travel the length of inland Madagascar, trekking 1,600 miles over eight mountains in 155 days in 2016.

The explorer said he had long been interested in becoming the first person to complete the trek along the Yangtze. “It’s one of the biggest things I can find that hasn’t been done yet,” he said.

In a photo posted on Instagram, Ash Dykes asks for directions to the source of the Yangtze. Photograph: Ash Dykes/PR Hunter/PA

He said he was drawn to these expeditions because he had “always been fascinated by the world”.

Describing the walking as “a bit boring”, Dykes said: “I love travel, meeting new people and taking on new challenges. This is what I do, it’s in my blood.”

He took note of the amount of plastics and pollution he saw from the source of the river to the sea. “The good news is that I’ve also seen a huge increase in knowledge and understanding within the communities, towns and cities along the way. People are aware of the damage being caused to their water sources and are now actively changing their ways for the better – it’s inspiring to see,” he said.

Dykes worked with the Green Development Foundation, WWF and other environmental organisations to highlight marine plastic, renewable energy and green finance. He was accompanied on the final kilometre by Chris Wood, the British consul-general in Shanghai.

Celebrating at the end of his 4,000-mile journey Photograph: PR

Dykes said he was overwhelmed by the response from Chinese supporters, with millions following him through TV and social media. “What a wonderful journey it’s been with incredible locals … People across the country have been so supportive.”

He said there was still much to discover in China. “I think I’ll be doing something again in China and try to make it more interactive, not only virtually, but in person too.”