Patrick Flinders was left disfigured in the August 5 attack on the island of Spitsbergen, when a 250-kilogramme (550-pound) male polar bear entered the camp site of 13 young Britons who were on a five-week expedition.
He punched the polar bear in the head as he fought for his life and was left with fragments of its teeth lodged in his skull as its jaws clamped down.
Horatio Chapple, 17, was killed in the attack. His funeral took place Friday.
Flinders, from the Channel Island of Jersey, had been sleeping next to Chapple when the bear attacked.
"I looked up and saw its huge mouth snapping. All around its nose there was blood. At that moment I thought I might die," he told the Sunday Mirror newspaper.
"It hit me with its paw and my arm came out of my sleeping bag. Then I felt its teeth around my elbow, biting down on the bone.
"Then suddenly it had my head in its jaws and I could feel it crunching my skull. I could hear it crack. I heard a growl which was deafening because I was so close up.
"I lashed out and waved my arm up to punch the bear in the head, again and again to get it off me."
Chapple was killed and two others besides Flinders were also seriously wounded. One of the expedition leaders, who was among those injured, eventually shot the bear dead.
Flinders has 20 staples on his skill, leaving a big scar across his forehead, his left eye is twisted and his ears and cheeks bear fresh scars. He will need further surgery to realign his eye.
He refused to accept he was a hero for hitting the animal in a bid to scare it off.
"I'm not a hero," he said.
"I punched the polar bear because I was fighting for my life, not because I wanted to fight it."
Flinders said Chapple was the victim of "pure bad luck".
"If I had slept where he was, I would be dead. I feel guilty it was him and not me."