A man who has made his living out of living like a castaway and exploring deserted islands has shared an incredible survival tip for making fire.

Alvaro Cerezo, 36, who used to work as an economist, explores the world’s most untouched beaches, and his time in the wild has taught him some pretty useful tricks.

He has shared this incredible video on Facebook showing how you can light a fire using a plastic bag and water.

He gathered a modest pile of coconut husks and filled a small plastic bag with seawater.

He then held the plastic bag over the coconut husks, using it as a magnifying glass to channel the sun’s rays onto the dry debris.

Within seconds, the debris caught alight.

Mr Cerezo said: “I have used this method to make fire so many times.

“People are usually surprised you can use a plastic bag to make fire – they normally cannot believe it.

“If explorers don’t carry plastic bags with them, there are always some on the shore of any desert island that have been pulled from the sea.

“The problem is most of them have little holes which would make the coconut hair wet, meaning it would be impossible to start a fire.

“Because of this you need to be lucky to find the right plastic bag, as it also must be transparent.

“Once you fill it with water – either fresh or salty – you need to create a round shape by pressing the sides.

“Then, the water creates the same effect as a magnifying glass.”

Mr Cerezo’s company, Docastaway, offers keen explorers the opportunity to be a castaway on a desert island for a few days.

He said: “Desert islands and that feeling of being shipwrecked have been my passion since I was a little boy exploring secret beaches and deserted coves.”