Andi Bauer, 26 and his partner Lara Booth, 23, were in southern Romania for a five-day expedition when they found themselves standing yards away from the animal, which had two cubs.
The animal immediately attacked Mr Bauer wrapping its jaws around his right leg and tossing him from side to side.
His partner Ms Booth, who had been walking behind him screamed for him to “punch it in the eye”.
When the animal attacked for a second time, Mr Bauer aimed for it’s eyes, and after he hit it, the bear fled.
Immediately after the attack, which left his leg badly broken and missing a chunk of his calf muscle, Ms Booth had to leave him to find phone signal to call the emergency services.
To stem the bleeding while she was gone he used his socks as a tourniquet.
Mr Bauer, who is from Germany, said: “I was in a state of shock, so I don’t remember the pain anymore.
“But this momma bear was suddenly a metre away from me. It was so loud.
“I had my side turned away from it, so when I saw it bounding towards me I just didn’t have time to think about what to do.
“It bit my leg, held on to it, and dragged me and threw me about.
“I was crying out for help, but there wasn’t anything that anyone could do.
“The bear let go of me, and after Lara told me to punch it in the face, I hit it. It then went away.”
He added: “I suppose I’m lucky I got through it. But I’d have been luckier not being attacked.”
Ms Booth, who is originally from Cambridge, added: “I was frozen with fear when we first saw the bears.
“I was probably useless – I was screaming at Andi the whole time.
“Keeping calm during an attack like that is hard. I did so as best I could.
“Then I remembered that you’re supposed to punch a bear in the eye, so I yelled that and the bear turned around and left him.
“Andi’s so lucky to be alive.”
Ms Booth had to walk for an hour up the mountainside to get telephone reception and eventually a helicopter arrived to pick her up before they flew down the mountain to retrieve her partner.
X-rays in hospital revealed his leg was shattered in three places, and he was given an external fixation to his bone – a cage around his limb.
Mr Bauer was later repatriated back to Munich, where he is still in hospital.
Ms Booth said: “This was supposed to be a hard but pleasant hike through the Romanian mountains.
“I’d read up about bears and panthers, but Andi had persuaded me not to bring a bear spray because he thought it’d be more likely that it would explode.
“I’d had a bad feeling deep down the whole time.
“Leaving him on the mountains on his own was the hardest thing I’ve ever had to do.
“To keep him safe, I told him to keep speaking loudly to scare other animals off. And the whole time I looked for help, another thunderstorm was gathering.
“It was a race against the clock at that point. But we won that one.”
Mr Bauer added: “I was always feeling optimistic that I would survive the attack.
“In fact, the greater risk was the helicopter not being able to fly through the mountains.
“The chances of being attacked by a bear like that are slim anyway – you’re more likely for the bear spray to explode than be attacked.”
Over 6,000 bears are estimated to live in Romania, mostly spread across the length of the 500-mile Carpathian mountain range, and attacks are relatively common.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies