RAF's 24-hour run on Anglesey coastal path
A team from RAF Valley has run the 131 miles (210km) of the Anglesey coastal path in 24 hours.
Some 55 runners took part in various sections of the run, including a night-time section on the east and south-east of the island.
Money raised will go to Llanberis Mountain Rescue Team and the relatives' room at the intensive care unit at Ysbyty Gwynedd, Bangor.
All the runners were back at the base by 1200 BST on Tuesday.
"When we started on Monday it was a glorious day but the heat made it hard work," said an RAF spokesman.
"Overnight it was cooler but hard going because of the terrain," he added.
Meticulous care had been taken with safety, and runners for the night section each wore head torches.
"We are always looking for interesting ways to raise money for charity whilst also challenging those taking part," the spokesman added.
"There is a real sense of achievement for those taking part - both in terms of personal times, and also in the team work."
There might also be a re-run some time in the future because the RAF has been unable to find any examples of the coastal path being run in 24 hours before.
"In the future it might be an invitational challenge," said the spokesman.