A 22-year-old man has been airlifted to hospital after he injured his back and hip during a fall near the top of the Neath Valley.
The man was winched 230 ft into the rescue helicopter
It is understood the man was canyoning with a group of 12 people.
Forty members from three mountain rescue teams, and a helicopter crew from RAF Chivenor in north Devon, were called at around 1700 GMT on Saturday.
The man was winched 230 ft (70m) into the helicopter and flown to the Prince Charles hospital in Merthyr Tydfil.
The members of the Brecon, Central Beacons and the Western Beacons mountain rescue teams were called to an area of the Neath Valley, between the village of Pont Nedd Vaughan and the Ystradfellte waterfalls, at around 1600 GMT on Saturday.
Paramedics were also called, but had to remain in Pont Nedd Vaughan because the area was inaccessible.
RAF Chivenor was called at 1700 GMT and a helicopter from there had to drop its winch in darkness to reach the injured man.
Huw Jones, from the Central Beacons Mountain Rescue Team, said the injured man was believed to be from Oxford and was taking part in an organised event.