The course is a bit different from your stock-standard marathon track.
While it has the same length as a normal marathon (42km), the terrain athletes have to contend with is quite novel.
"The terrain is very tough. You have to run over ice, rock, moraine, dirt, sand and mountainous open plains.
"You also have to traverse technical, steep downhills next to deep valleys and contend with high volumes of yak and mule trains, as well as other climbers and trekkers."
Douglas ran a time of 6:34:05, finishing 12th in the international division and 35th overall. Karyn Douglas, Chris' wife, finished fifth in the half marathon event.
Of those who competed, between 40 and 50 are Nepalese and the rest come from across the world.
Douglas was the Northlander out of the three New Zealanders competing in the full marathon.
Despite the rough track he raced on, Douglas said the run wasn't the toughest aspect of the event.
"The hardest part was getting to the start of the race," he said.
"The race starts at the Mt Everest base camp so it took us 12 days of trekking to get to the start line. We stayed in a series of tents on ice and rock."
The race isn't just dangerous in terms of the terrain.
Because of the high altitude, competitors are susceptible to altitude sickness.
"We had three in our group taken out by helicopter because of it. There were also bugs going around so people were vomiting.
"Dietary conditions were out of our control so that may have played a part."
The next Tenzing Hillary Everest Marathon takes place on May 29 next year.
