He has survived injury, isolation and an awful lot of drenching, bone-chilling rain, and now Will Renwick is on the point of completing an extraordinary run across Wales, taking in 189 mountain peaks.

Unsupported, carrying his tent and everything else on his back, the 31-year-old will have run south to north, covering more than 500 miles, and in the process raised thousands of pounds for the charity Mind Over Mountains, which promotes the benefits of spending time in the great outdoors.

Renwick, the president of Ramblers Cymru, began his journey on 10 September by heading north from Swansea in south Wales. He turned east and traversed the Brecon Beacons before squiggling his way through mid Wales – the country’s “green desert” – and tackling the mountains of Snowdonia in the north. He is due to finish in Conwy on Sunday or, if the weather gets really rotten, first thing Monday.

His ankles are aching, he has holes in his feet and his one lighter has broken, meaning he has had to eat “boil in a bag” meals cold. But he said: “The idea of a gigantic, never-been-done-before adventure within my home country really appealed to me, especially if I tied it to a charity with a cause close to my heart.”

By the second day he was not sure he would complete the run. “I was thinking I might have to drop out straight away,” he said. His left knee had started to trouble him, which led him to put too much pressure on his right leg, and he was left with such a sore ankle that he thought he might have to give up. “But I iced it and gradually the injuries have disappeared. It’s amazing how the body can heal on the go. My body has really surprised me.”

He is following a route called the Dragons Back Challenge, which two walkers, Michael Myerscough and Michael Murray, hiked in 34 days in 2018 to raise money for mountain rescue.

Renwick, the editor of Outdoors Magic magazine, would have liked to walk it. “But I couldn’t justify that much time off work so I decided to run.”

The logistics have been tricky. “Resupplying, keeping batteries topped up, it’s been the sorting out that has been difficult.”

It is also a challenge to make sure that every mountain is ticked off. Myerscough and Murray climbed 190. Renwick called his challenge the “190 run” but the list is a movable feast. The website go4awalk.com, which Renwick has used, lists 188 “Nuttalls” in Wales – mountains and “subsidiary tops” over 610 metres that rise above their surroundings by at least 15 metres. Renwick has fastened on 189.

Often the going has been tough. “In mid Wales the hills are so untrodden that there is no proper track. You have to break trail yourself, carve your way through, which can be exhausting. On many stretches I did not see a single person.” Renwick, who is from Llancarfan, south Wales, has found himself talking to the sheep, the red kites, the buzzards.

There have been some demoralising moments, such as a rare trip to a pub in Beddgelert, Snowdonia, after running more than 20 miles over a group of mountains called the Moelwynion only to find the kitchen had closed. “Fortunately I had sandwiches and pasties given to me by sympathetic strangers.”

But the glory of the landscape kept him going. In 2013, Renwick walked around the perimeter of Wales via the coastal path and the Offa’s Dyke route. “I’ve done a lot of walking and set out on this thinking there wasn’t much that would surprise me. But I was surprised every day by valleys, vistas, hamlets tucked away, fascinating little corners.

“The variety is astonishing. One morning you’re in rolling upland pastures, then you emerge into a landscape that feels like the Yukon. Wales is not just one homogenous set of hills; each range has its own charms.”

Far from the madding crowd

The most famous Welsh mountains such as Yr Wyddfa (Snowdon) in the north and Pen y Fan in the south can be terribly crowded. Here are four of Will Renwick’s highlights off the beaten track.

Radnor Forest An often forgotten corner of Wales. A forest in the medieval sense – a wild place set aside for hunting. Great views from here of the Brecon Beacons and the peaks of mid Wales but also across the border to the Malverns in Worcestershire and the rolling countryside of Herefordshire.

Moel Llyfnant A peak in the Arenig mountain range in the southern portion of the Snowdonia national park. It reminded Renwick of a mountaintop in the Dolomites, a sharp point approached via scree slopes and boulders.

Y Garn A huge craggy cliff defends one side of this mountain in the Rhinogydd range of north Wales. It is full of tunnels and old gold mining spots. The “honeypot” mountains of Snowdonia are not far away but you are not likely to see anyone here.

Pumlumon Almost slap-bang in the middle of Wales, the highest point of the Cambrian mountains. The rivers Severn and Wye have their sources here.