Why did three young men climb the highest mountain on mainland Spain wearing just shorts, boots and hats?

Three young men have climbed Mulhacén, at 3,478 metres the highest mountain on mainland Spain, completely topless, wearing just shorts, boots and hats.

The 21-year-olds from Granada Pablo Linares, Julio García and Luis Torralba, documented their journey on YouTube and said they wanted to "push the limits and the comfort zone of each one of us".

They hiked Mulhacén on New Year's Eve and slept in a Civil War bunker at the top of the mountain in the snowy Sierra Nevada, before returning the next day.

Linares said they physically prepared themselves for the journey, had access to a guide and each carried around 300 euros worth of survival gear in the event of an emergency. "If any of them had had a hypothermia problem, we would have reacted instantly because we even had heat patches that are more useful in these cases than the clothes themselves, which we also had," he said.

Some critics have outed the men for the ambitious journey as "dangerous" and "reckless", but Linares pointed out it was not a challenge to go viral or attract attention as "it would be reckless for others to climb Mulhacén without any physical preparation". "We were able to withstand the cold better than other people because of this previous training," he added.

Linares said they plan to go on more challenges, such as swimming across the Strait of Gibraltar, and document them via their social media pages: A modo nuestro.