More than 50 youngsters taking part in this year's Ten Tors challenge had to be taken off Dartmoor with "minor injuries".
Around 2,400 youngsters took part in the Army-led trek across up to 55 miles across the southern English moors.
Spokesman Ronnie Jones said the 53 had minor injuries such as the "usual sprains, strains".
He said: "The youngsters have been training for this throughout a pretty horrendous winter so they won't be strangers to wind and rain.
"It's called a challenge for a reason, it is arduous going."
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Dartmoor Zoo has said that it will close tomorrow due to the concerns about the weather.
Police have launched a murder investigation following the deaths of a mother and her son at Dartmoor and the discovery of a second child at the family's home.
The 24-year-old woman, named in reports as Katharine Hooper, and her five-year-old son died after falling from rocks at Haytor in Devon - one of Dartmoor's most famous landmarks which is popular with walkers and climbers.
The body of a two-year-old boy was later found at her home address in Dukes Close, Paignton.Devon and Cornwall Police said they have launched a murder investigation led by the force's major crime investigation team.
Officers investigating the deaths of a 24-year-old woman and her five-year-old son in a fall at Haytor on Dartmoor have found the body of a two-year-old boy, also believed to be her son, at her home in Paignton.
Police say post-mortem investigations on all three will be carried out in due course. Their next of kin has been informed.
A woman and her young son have been killed after falling from rocks on Dartmoor, police said.
The 24-year-old woman and her five-year-old son died at Haytor, which is one of Dartmoor's most famous landmarks and is popular with walkers and climbers.
Police said the incident happened at 11.50am on Friday with reports that the mother and son fell from the rocks.
An air ambulance, a police helicopter and members of the Dartmoor Rescue Group went to the scene.
Acting Chief Inspector Adrian Leisk is from Devon and Cornwall Police:
Police say seven teenage boys have been airlifted to safety by helicopter after getting lost on Dartmoor. The 14-year-olds were practicing for the annual Ten Tors trek across the national park when they became disorientated in low cloud yesterday afternoon.
The boys were from a school in Wiltshire.