When signs of frostbite forced Mr Jeremy Tong to turn back when he was just 150 minutes away from the top of Mount Everest in 2017, the failure haunted him for two years.

Last Wednesday, the Singaporean co-founder of an adventure company laid the ghost of his failure to rest by conquering the world's highest peak.

Achieving this feat was anything but easy. Coping with freezing conditions and extreme exhaustion was par for the course for anyone seeking to conquer Everest.

But this time, Mr Tong, 28, had to contend with another challenge - a human traffic jam resulting in a snaking queue of climbers in their final push to reach the top. Mr Tong, who had to queue for a number of hours and even at night, recounted a point where he was trapped in the single-file queue along a particularly treacherous part of the trail.

He told The New Paper over the phone in Kathmandu, Nepal: "If you fall, you will plunge 2km into Nepal on your left or the same height into China on your right.

"There was no room for error. You could easily fall to your death, your oxygen (tank) could malfunction or the weather could change - there were so many things that could have gone wrong."

Mr Tong left Singapore for the expedition, which he had dreamt about for five years, about two months ago, after his first child was born.

While it was difficult for him to be away from his newborn son, his thoughts of the baby helped him meet the challenges he faced along the way.

During his first attempt, in 2017, Mr Tong had seen several dead bodies on his way up and understood that danger, and possibly even death, was part of the process.

"This year, more than ever, it was crucial for me to make it back down the mountain for my son and his future," he said.

Ten climbers have either died or are missing on Everest so far this year, the highest toll since 2012, when there were 10 deaths.

The bottlenecks on narrow trails caused many climbers to be stuck at high altitude for extended periods, which is dangerous to the human body.

Mr Tong said: "It was frustrating because climbers move at different speeds, and there was only one way up. At night, when it's freezing cold and you have no food and are exhausted, it gets really frustrating to not be moving.

"Not moving in minus 40 deg C weather meant I was at risk of frostbite, so I kept flexing my fingers and toes.

"The only way to move or to leave the queue was to try to make a new path. At night, when you're so tired, one misstep and you could die."

Mr Tong said the high number of deaths this year also affected him because he had known and climbed with some of the people who died.

"Because I knew them, it affected me. We had been climbing together at some point. It was scary because you realise that it could have been you. There were so many things that could have gone wrong."

As in his first bid, Mr Tong also made this climb for charity - he said he has raised about $11,000 for the Children's Cancer Foundation.

Climbing for cancer was meaningful to him as his uncle had suffered from nose cancer. Hearing his uncle recount his battle to survive the disease had a profound effect, he said.

Mr Tong added that he saw parallels in fighting cancer and climbing a dangerous mountain in that they were both battles that could make the difference between life and death.