And although they cannot compete with aeroplanes for speed, or with water-borne shipping for volume, they could cover in a few days a distance equivalent to a six-week journey by ship.

ECONOMIST: Pushing the envelope

Chronic hypobaric hypoxia (lack of oxygen): where the expedition will encounter equivalent altitudes up around 3, 800m due to the extreme cold temperatures and distance from the Equator which further decreases atmospheric pressure.

BBC: Viewpoint: The last great polar challenge

The Marathon des Sables covers a distance of 151 miles (243 kilometres) in six days - the equivalent of nearly six regular marathons.

BBC: Bristol - Woman back from Sahara desert race

The North Antrim representative said illegal nets had been seized in the lough equivalent to running a net from Belfast City Hall to Ballymena Town Hall, a distance of around 30 miles.

BBC: Sustainability of indigenous fish stocks