Sporting the same outfit – grey top, blue denims and even matching emerald contact lenses – they speak with passion about mountains . In April, Nungshi and Tashi Malik, twins from Sonepat, Haryana , became the only Indians - in fact, the only south Asians - to complete the Explorers Grand Slam – the South and North Pole, and the seven summits. All of 23, they're also reportedly the youngest in the world to achieve the feat.

What started as a casual vacation course at the Nehru Institute of Mountaineering in Uttarkashi in 2009 soon turned into an obsession. They went back next year for an advanced course and climbed Mt Rudugaira (5,490m).

The twins were quick to set their eyes on the highest of them all - Mt Everest. While for Nungshi, it was about proving a point on behalf of all girls, for Tashi Everest was literally a recurrent dream. But not everyone was on board. "Mum would quietly go up to the instructors and tell them to fail us," says Tashi. But by 2012, they had aced their tests and proved that they were ready. Money was still a problem though. With no sponsors, their once-reluctant mother took a loan and their father, an Army man, put all his savings at stake. The lanky girls climbed Everest on 19 May, 2013, along with Samina Baig, the first Pakistani woman to achieve the feat. It was on the way back to base camp that fellow mountaineers sowed the seeds for their next dream, the 7-summit challenge - climbing the highest peak in each of the seven continents. "We took it up to raise awareness against female feticide," says Tashi. Today, as ambassadors of the 'Beti Bachao' campaign, they deliver motivational speeches to schoolgirls.

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But being a woman mountaineer comes with its bunch of prejudices. They are generally treated as the "delicate members" of the crew but once the climb starts, they prove tougher than most of the men. "We've been given all sorts of nicknames, like Rajdhani-Shatabdi Express for our swift pace," says Nungshi with a chuckle.

They also have a rigorous training regimen, which includes a 15-20 km jog every day, yoga, muscle strengthening exercises, and tyre-dragging sprints. "We're about 57 kg each and while skiing to the poles, we were pulling around 65kg in sledges for 9-10 hours a day," says Nungshi.

But physical fitness is not all that one requires in these extreme conditions. "We've lost 25 of our climber friends in the last one and a half year," says Nungshi, who says mental readiness is a key factor. The usually cheerful twins leave loving notes for their parents before embarking on these dangerous missions, knowing that they may not come back.

After all, death constantly lurks around them. In Antarctica, the twins faced temperatures of up to minus 60 degrees Celsius and wind speeds of about 70kmph. "North Pole was even more difficult since the ground wasn't stable; we navigated running water by hopping on floating ice slabs, 3 metres thick," says Nungshi.

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While Everest was certainly the toughest peak, Mt McKinley in North America wasn't far behind. "We were stuck in a snowstorm for two days and were running out of ration," they recall. With just one more day's permit left to try the climb, they went for it and achieved the feat but that also meant a non-stop descent for 36 hours. A 7-8 day trek to the base camp of Carstensz Pyramid in Indonesia featured dense tropical forests, cannibalistic tribes and waist-deep mud pools. On the way back, they suffered from hallucinations, wandered off the track and barely escaped drowning in a river.

So what keeps them going? The cause they work for, and a 23-year-old bond. "While climbing, you need someone you can trust. Who better than a twin?" says Tashi. They've literally stepped on the summits together, taking care of each other along the way. The twins' lives have been so entwined that their social life is limited. "We've never dated anyone!" says Nungshi, adding, "We enjoy the twin branding but maybe it's time we part ways in our careers and find our own individual selves." The girls are pursuing a course in sports and exercise physiology in New Zealand. They're also setting up the NungshiTashi foundation to promote mountaineering as a sport.

But climbing is a drug, say the twins who will continue to scale peaks. So what's next? "Mt Cook in New Zealand and a few virgin peaks around the world," says the pair, as casually as picking out new shoes.

(With inputs from Anandamayee Singh and Zahra Rizvi)