If he hadn’t lost a leg in a train accident a decade ago, 35-year-old Uday Kumar would never have thought of doing the marathon.

Or conquering mountain, sky and ocean — all at one go — as the young Calcuttan did last month in Africa.

As part of a six-member team from the Himalayan Mountaineering Institute (HMI) here, Uday climbed Mount Kilimanjaro — dragging himself up 19,341ft on crutches that repeatedly got stuck in the volcanic ash — and then tested his skydiving skills over Tanzania after just four days of training. He rounded it off with a bout of scuba diving in the Indian Ocean off the Zanzibar archipelago.

Uday, whose day job as a data entry operator with a private firm appears strangely incongruous with his adventure-soaked parallel life, said his accident happened in 2015.

Travelling on a train in Calcutta, he was using the washbasin near the door when a jerk flung him outside, onto the tracks, with one of his legs coming under the train’s wheels.

It transformed the life of the then office peon-cum-pantry boy from one of content to one marked by the seeking and conquest of challenges.

“I turned my disability into my strength,” the young man from Belghoria told The Telegraph over the phonefrom Calcutta.

He thanked the HMI principal, Group Captain Jai Kishan, who led the expedition while training and guiding him every inch of the way.

Technically, the expedition was styled “Kanchenjunga-to-Kilimanjaro” or K2K. It began in March this year, with the HMI team helping Uday climb Mount Rhenock (16,500ft) at the Kanchenjunga National Park in western Sikkim. The African leg camein August.

Apart from Jai Kishan and Uday, the team to Tanzania was made up of Captain Shruti S. Chanaveeragoudra and Sulaxchana Tamang (Everester) — both women — Subedar Mahendra Kumar Yadav and Pawel Sharma of the HMI.

Uday said that conquering Kilimanjaro proved more difficult than his shot at skydiving and scuba diving, although he was a novice in the lasttwo sports.

“The landscape there (Kilimanjaro) is different, with no trees. I had difficulty breathing. The last 500 metres were hard and I suffered from mountain sickness. I could see and hear everything but could not react,” he said.

“The terrain was rocky and my crutches would get stuck in the volcanic ash.”

He said that pulling the crutches out ate up time and drained his energy, while causing significant strain to his upper body, including the shoulders, elbows, wrists and palms.

“My teammates, especially our leader, Jai Kishan Sir, egged me on the way parents encourage toddlers to take one step at a time. I thought time had come to a stop,” Uday said.

After the descent, Uday had to be moved around in a rescue trolley for a coupleof days.

Three years after his accident, Uday had begun running the marathon on one leg and became a well-known face on the circuit.

About two years ago, “Uday himself approached the HMI and wished to take part in adventure sport; we made a special provision to train him over the years,” JaiKishan said.

At Kilimanjaro, it took the team 10 hours — double the normal time — to reach the top from the last camp, having started at 3 in the morning. The descent to base camp took seven hours.

Atop the mountain, the team unfurled a 7,800sqft Indian flag to celebrate the country’s independence, which is in its 78th year.

“This was a dream, a journey for me to climb from zero to the top, to the top of my dream,” Uday said.

Having done Kilimanjaro on August 8, the team arrived in the Tanzanian capital,Dar es Salaam.

“There, we organised four days of special skydiving training for Uday,” said Jai Kishan, an expert skydiver, parachute jump instructor and mountaineer who holds six world records, an Asian record and six national records in adventure sports.

“When Jai Kishan Sir jumped and said, ‘Follow me’, I was a bit scared. But I was confident that nothing bad would happen to me,” Uday said.

After four skydives from 9,000ft by Uday and Jai Kishan – marked by displays of the Indian flag in the sky — the team travelled to Zanzibar for a spell of scuba diving.

“I was confident after my four-day training there. However, once I started diving deeper, my ears began hurting and I thought the pressure was hitting my brain,” Uday said.

“Still, I enjoyed my 35 minutes under the sea. I had seen marine life only on the Discovery channel before, but this experience was wonderful.”

The team — Pawel participated in the scuba diving with Jai Kishan and Uday — unfurled a 780sqft Indian flag in the Indian Ocean.

The team was sponsored by the defence ministry. Sources said it was rare for the ministry to sponsor a civilian from outside the HMI.

“The expedition was meant to highlight the strength and spirit of the differently abled community and emphasise national pride and inclusivity,” said Jai Kishan, a recipient of the Tenzing Norgay National Adventure Award, the highest honour in adventure sports in India.