Over the past few months a team from the Brecon Beacons National Park have been airlifting nearly a thousand tonnes of stone and heather to repair the damaged landscape.
From the air you can see the bare and barren bogs of peat. They've been eroded by years of harsh weather and the footsteps of walkers.
Watch: Hannah Thomas reports from the Brecon Beacons
The work they're doing will help the local wildlife. It'll also reduce carbon dioxide emissions and tackle flooding much further down the valley.