A British army captain attempting to become the first person to make a solo crossing of Antarctica says his body is "taking a hammering".
Captain Louis Rudd, 49, has just passed the South Pole as he aims to take the lead over an American rival also vying to complete the 1,500km challenge.
Rudd told ITV News of the tortuous conditions he is enduring - including temperatures averaging -25C and constant daylight - as he drags a sled using just a pair of skis.
Rudd, who has toured Iraq and Afghanistan with the Royal Marines, began the challenge on November 1 and hopes to complete the race in approximately two weeks.
He and Colin Brady, 33, are only the third and fourth people to attempt the journey. One quit after 52 days and the other died.
Rudd told ITV News that dragging his sled, which at the start of the journey weighed 140kg, requires a "huge amount of effort".
Comparing it to "dragging a bathtub with somebody in it through custard", the army captain says the load had only become easier as he slowly uses up his supplies.
The strain of carrying the sled, which contains a tent, cooker fuel, and food suppliers among other things, means Rudd is consuming around 6,000 calories a day.
But despite this, he has still lost more than 10kg in body weight.
"Basically when I finish each day, after about 12 hours of skiing, I set the tent up and I put the cooker on and I melt snow," Rudd says, describing his daily routine.
"I melt enough snow to make boiling water which I then add to the food dried meals which reconstitutes them."
Rudd admits that the difficult conditions have taken a toll on his health the longer the race goes on.
Medical issues he has suffered include "lots of blisters", infections, slits on his hands and severely blistered lips after his mouth reacted badly to the cold.
The 49-year-old says he manages about six hours of sleep a night and sets his alarm for 6am daily.
Rudd says that some of the most challenging conditions have been during whiteouts, or heavy blizzards, rendering visibility almost impossible and occasionally lasting all day.
"Whiteout is particularly difficult," Rudd says.
"Essentially you don't get any sunlight coming through at all. You basically lose all visibility, so you literally can't see the ground or the sky or anything at all.
"Essentially it's like being inside a ping pong ball."
Rudd says in that scenario he has to "feel his way out," relying solely on his chest-mounted compass.
Currently on the Polar Plateau at an altitude of 9,500ft, Rudd is making his way towards the Transantarctic Mountains and the Leverett Glacier.
To help keep his spirits up Rudd is writing a diary and has an iPhone "full of" audio books and music.
"I find audio books really good and quite comforting to have a voice and hear someone talking to you," Rudd says.
"I like listening to biographies of Winston Churchill and my old World War Two history books."
Rudd and Brady's journeys began on the Ronne Ice Shelf in the Weddell Sea and will hopefully end on the Ross Ice Shelf.
Rudd was made an MBE on October 17.
To follow Spirit of Endurance and Captain Louis Rudd's every step: visit: