Tiny villages are scattered along the gorge, which rises from the apple and pear orchards and the gray stone riverbed of the valley floor to heights of more than 2,000 meters (1.2 miles) above sea level.
Many of these villages, which were bustling communities in the 19th century, now lie abandoned or survive with just a handful of inhabitants.
One dead-end road, the D107, winds its way through Prads-Haute-Bleone, passing churches and a campsite that offers a peaceful retreat for summer hikers.
But the remoteness -- which appeals to small numbers of holidaymakers looking to ski in winter or take restorative walks through the green hills in the warmer months -- may make reaching the wreckage of the Germanwings plane difficult.
Gilles Gravier, director of the tourist office in Val d'Allos, told French newspaper Liberation
the crash occurred in a particularly steep spot on the Trois Eveches mountain, and may have been witnessed by skiers on the area's slopes.
"There is no access by road; emergency crews are coming in by air, using helicopters," he said.
Capt. Benoit Zeisser from the Gendarmerie in the nearby town of Digne told CNN the aircraft was lying in "difficult terrain."
Sandrine Boisse, the president of the tourism office at the Pra Loup ski resort, said she heard the plane crash and called the police and the local government office to find out what had happened.
"It was about 11 (a.m.) here. I was outside the garage, and we heard a strange noise, " she said. "And at first we thought it was an avalanche, but it was strange at this time because it was 11.
"Something was wrong. ... We didn't know what."
Her husband was skiing nearby and saw a plane flying at low altitude, she said.
French President Francois Hollande warned "it will take some hours for the emergency services to reach the crash site."
Photographs posted on Twitter hours after the plane disappeared from radar showed helicopters preparing to take off, and emergency vehicles lining up ready to receive the victims' remains.
The bodies of those on board the plane are expected to be taken to the gymnasium at the local high school in Seyne les Alpes, some 10 kilometers (6 miles) from the crash site, which will be used as a temporary morgue.
French police in the region have pleaded with locals and visitors to stay away from the site, urging them "not to clutter the roads," leaving them clear for emergency vehicles.