Focus on ... Three Peaks Challenge

The event challenges participants to climb the UK's three highest peaks in less than 24 hours. It is also an opportunity for teams to raise money for charity.

- The trek involves climbing more than 3000m in 24 hours, walking on uneven land and hiking in the dark on varied terrain.

- British Military Fitness organises the event.

- To avoid ruining the countryside, those taking part in the event follow a 'country code'. Places are limited, regular routes are used and litter is collected.