With so many hills to choose from, and so little time in life, most walkers will be happy to visit a summit just once or twice. Anyone working through a tick list, for instance, is practically obliged to keep treading new ground. But for others there's an irresistible attraction in the familiar, and a rare few feel inspired to walk their chosen peak dozens or even hundreds of times. Does it ever feel like a Sisyphean task, or does every repetition offer something new?
Fiona Russell speaks to some extreme cases, people for whom the term "once or twice" has no meaning.
Hywyn Roberts has reached the summit of Snowdon (Yr Wyddfa) more than 1000 times. Yes, you read that right.
Living just five miles away, as the crow flies, the 59-year-old retired bank manager says he never tires of the 1085m tall mountain. In the last five years alone, he has walked to the highest point in Wales some 700 times.
He says: "Snowdon is nature's gym to me. It keeps me fit and I enjoy every ascent. They are all so different and in such varying weather conditions. I have also found many different routes, there are some 16 ways that I can get to the top, and I often take a different route down. Some people might say I am obsessed by Snowdon but I'm not; I just like it and it's so close to my home."
Hywyn first walked Snowdon as a teenager and, while he was working, he would summit the mountain 15 to 20 times each year. It is since retiring that his Snowdon tally has increased significantly.
He says: "I obviously have a lot more time now I'm not at the office every day – and my children have also left home. I do like other hills and mountains but I walk Snowdon the most frequently."
Snowdon is nature's gym to me. It keeps me fit and I enjoy every ascent
Hywyn walks Snowdon year-round. He says: "I like walking Snowdon in the summer very much but I also enjoy the winter as well. The views are always changing and so does the wildlife and the people you meet. It is always different."
He reveals his coldest day on the mountain was when temperatures plummeted to -32C with windchill. He says: "That was when Britain was hit by the Beast from the East in 2018. I have never know it so cold on Snowdon."
He walks most of his Snowdon ascents on his own although he does enjoy the company of other people, including friends and family. If he meets people on Snowdon he is keen to educate them about the geology of the mountain and, for example, the fossilised seashells at the summit.
Hywyn has also helped people who have got into difficulties. He says: "It is a good feeling to be able to assist people who have become caught in whiteouts, for example, to help them escape a situation they might have been able to deal with."
He has also witnessed an increase in the number of walkers on Snowdon. He says: "I think the footfall has probably doubled over the last five of six years. I think this is because more and more people hear about the tallest mountains and they want to visit and walk to the summit. I think people want to be healthier and to explore more in the outdoors, too. There are so many more people on Snowdon's main path than ever before."
But the numbers do not put him off. He says: "I will probably just keep walking Snowdon for as long as I can. It's so accessible for me and, quite simply, I enjoy it."
John McSporran has walked his favourite local hill Ben A'an more than 100 times in just a few years.
It took the Scottish photographer three years to climb the 454m that many times - and he is still at it. To date, John, of Aberfoyle, Stirlingshire, has walked to the summit 110 times.
The keen photographer said: "I chose Ben A'an as a walking challenge because it's close to my home and because it's not particularly high. I really like the hill and I have enjoyed being out in all kinds of weather and taking photographs."
Ben A'an, also known as the "mountain in miniature", is a popular hill walk and takes the average fit person about 60 minutes to get to the top. John said: "The hill is a steep lung-bursting climb at times. There is no 'ease yourself into it gradually' like many of the Glencoe Munros or even Ben Nevis."
For me Ben A'an is not a 'glass half full', it's a glass overflowing type of hill. I have greatly enjoyed walking it so many times and I don't think I'll stop any time soon
John's fastest ascent to date is 38 minutes, although he has also reached the top after a leisurely two hours of strolling with friends.
He has climbed the hill nine times with his daughter Eilidh, five times with his son Calum and three times with his wife Ann. He has walked it both in the day and at night and he has been faced with every kind of weather that Scotland can create, from snow to driving rain to warm sunshine.
He has wild camped on top in a winter storm and he was also fortunate to see a "fog bow'" wreath as sunrise struck the mountain top in mid-winter.
During his challenge, one of his Ben Aa'n photos reached the finals of Mountain Photo of the Year.
John said: "Ben A'an is a great walk at all times of the year and you always see something different. It offers a superb viewpoint, too. From the top the panorama is stunning and takes in many mountains such as the Arrochar Alps, Ben Lomond, Ben More, Ben Ledi and Ben Venue. On a clear day, it's also possible to see as far as the cities of Stirling and Edinburgh."
John has met thousands of people on the mountain during his 110 ascents. He said: "Everyone is very friendly when walking on Ben Aa'n and they are always willing to say hello. Among memorable encounters I've met a 50-member choir all the way from Holland, who sang hymns on the top. I met 200 members of a Glasgow mosque on a charity climb, including women in full burqa. I once saw a family trying to push a pram up the near vertical rock steps and a guy climbing it in stiletto heels for a bet."
Sadly, John also ended up injured on the hill after falling 100ft, and rupturing his medial and cruciate ligaments in the process.
He said: "I was my own stupid fault. I was paying attention to getting a photograph and not where I was standing. I managed to limp off but the injury halted my challenge for a while. I had to have surgery but I went on to walk the hill again and did my last three summits to reach the 100th ascent in October 2018."
John said: "For me Ben A'an is not a 'glass half full', it's a glass overflowing type of hill. I have greatly enjoyed walking it so many times and the chances are I will continue. In fact, I don't think I'll stop any time soon."
In total John's first 100 Ben A'an ascents add up to around four times the height of Everest.
Matt Le Voi has lost count of the number of times he has submitted Scafell Pike, but reckons the figure is more than 400.
Matt, of Allonby, Cumbria, says: "I have done most of my Scafell Pike ascents in the last eight years and I stopped keeping a record at 250 times around three years go. I still have a rough idea because I guide people as part of my work."
I have been on the mountain at every hour of the day and night. The views are always changing and this is amazing considering the hundreds of times I walk it
The 30-year-old began guiding in 2011. He is a summer and winter mountain leader and company director of Lakeland Mountain Guides.
Before he started guiding he had reached the summit of Pike only a few times. Once, he took part in the Scafell Pike Mountain Marathon.
He says: "It's because of all the people who want to walk Scafell Pike that I have not been to the summit more than 400 times and many times each month, especially in the summer. Some 85% of clients want to walk Scafell Pike simply because it is England's tallest mountain; and why not? It's a great mountain for guiding on and the views are brilliant."
Matt thinks Scafell Pike is a good mountain for guiding people of different experience levels. He says: "The mountain can be a great introduction for some people who have not been in the mountains many times and for others, who have more experience, there are some challenges and technical aspects.
"I think my favourite is the southern approach, from Eskdale, with waterfalls and the valleys. And I also look forward to the challenges of the winter season."
Although he has walked Scafell Pike many times, Matt still finds plenty to enjoy. He says: "I can ascend the mountain in good conditions without really thinking so much but because the weather and seasons change, then there are many fresh challenges and rewards.
"People rely on me to be safe and to enjoy the experience of reaching the summit. But it's in the winter, when there are more skills and experience required that I enjoy being on Scafell Pike the most. It's great to be technically challenged, perhaps in snow, ice or a white-out."
Matt enjoys meeting different people, too. He says: "It is rewarding to guide such a range of people on Scafell Pike. They come for many reasons and to see how pleased they are to reach the highest point in England is a great thing. I think it's the people that make my multiple ascents of the mountain seem fine."
In addition, Matt is never tires of the views. He says: "Each day is different and I have been on the mountain repeatedly at every hour of the day and night. The views are always changing and this is amazing considering the hundreds of times I walk it.
"Of course, there are plenty of other great hills and mountains in the UK, but I would have to say that Scafell Pike is a favourite."
Alister Stewart, of Carnwarth, South Lanarkshire, set himself a 50th birthday challenge - to reach the summit of his local hill Tinto 50 times. Between January 1 and May 18, the day before his birthday this year, he managed it...
He averaged three climbs each week and on one occasion he walked the 711m hill twice in one day, each time notching up 470m ascent over about 4 miles.
Alister, a validation engineer for the NHS, said: "I was looking to do something special to celebrate my 50th birthday; something that I could do on my own or with others, so climbing Tinto 50 times between January and May was perfect.
"I like to challenge myself physically – and mentally – now and again. In the past I've walked or run a minimum of three miles a day for 100 days in a row. The aim of the birthday challenge was to ascend Tinto Hill 50 times from the car park to the cairn."
Tinto, which is classified as a Graham, has long been a favourite hill for Alister. Originally from Lanark, he has known of the iconic Clydesdale hill for as long as he can recall.
I like to challenge myself physically and mentally now and again
He said: "As a child, I was aware of Tinto from an early age and I am still walking it today so it has a special place in my heart. I'm also a member of Tinto Hill Runners so I've been up and down many times in the past, and I'll no doubt be up a few more times in the future."
Alister walked the first of his 50th challenge on New Year's Day with his 75-year- old dad Donald. Donald was also there on the 50th climb, alongside Alister's 13-year-old twins Harry and Molly and around 20 other friends and family.
Alister said: "Actually my kids had already climbed Tinto that day with their school as part of a sponsored walk for charity. Then, they were back up it again that evening for my 50th one."
Alister said the weather was mixed throughout the 50 climbs of Tinto but never too testing. He said: "I was fortunate with a fairly mild winter, which allowed me to reach 24 climbs by the end of February. The best climbs were the ones during clear, crisp and frosty nights. I can't really fully explain the buzz that I got during evenings like those."
"However, my work was probably the hardest thing. Being a service engineer is not a nine-to-five job, so my plans were often rescheduled. I went up twice in one day and one time I went up four days in a row just to get back on schedule."
Alister's fastest ascent was 32 minutes and the quickest descent was 16 minutes. He said: "Before I started the challenge, my fastest time walking to the top was 45 minutes and by the end of it I was regularly walking up in under 40 minutes. My fitness definitely did improve, however I'm still suffering from tendinitis in my Achilles from all the descents which is not so good."
In total, Alister ascended 23,500m and covered 210 miles over the 50 Tinto hill climb challenge.
Rich Pyne has summited Ben Nevis 358 times... and counting.
Rich, 45, is the owner of outdoor adventure company, Rich Mountain Experiences. He is also the founder of The Real3Peaks Challenge, an annual mass volunteer litter pick on the UK's national high points.
Living in Kinlochleven, in the Scottish Highlands, Ben Nevis is easily accessible and only around an hour's drive away. Rich has worked in the mountains for the past five years and he has summited the mountain with customers many times, however he has also reached the summit on multiple occasions for personal pleasure.
The first time I reached the summit I had been inspired because it is the biggest UK mountain. Now it's my work, and I am fortunate to meet lots of interesting people
The first time up he was aged 24. He says: "Back then, I remember, I bobbed up the Pony Track, then headed around the Carn Mor Dearg Arete. These days my work includes the Ben, as well as many other hills. I'm am out in the hills most days of the week, particularly January to end of November and I can accumulate 200 to 300 hill days a year.
"Summer is the busiest time on Ben Nevis and I work with private groups and National 3 Peaks Groups, so I can do between four and eight ascents of the Ben a week, sometimes three in one day. My last ascent of the season is often part of The Real3Peaks Challenge, which I started in 2013."
A large number of his ascents are via the tourist trail, also called the Pony Track, because of his work, although Rich does enjoy a more challenging route via the Carn Mor Dearg Arete.
He says: "The CMD Arete is always a winner for me. I have been all over the Ben all year round, with winter being my favourite season there."
Rich enjoys ascending Tower Ridge too. He says: "Tower Ridge is not too difficult, if you've got the skills, and the situations are stunning. I thoroughly enjoy taking friends up that route, with one of the most memorable ascents with my wife one October. We had the entire mountain to ourselves, and the weather wasn't even bad."
Sometimes, perhaps on the third ascent of the day, Rich admits he can tire of the same route on The Ben but he says that because he is usually there with different and interesting people, every time is different.
The changing seasons and Scotland's fickle weather means that Ben Nevis still holds his interest. Yet, some summits have remained in his memory more than others. He says: "A favourite ascent was a couple of years ago, on the Summer Solstice Sunrise Event that we organise. We had about 20 people up there for the best sunrise ever. A cloud inversion going on all around us, no wind and not a sound. It was a very special morning."
Rich recalls another memorable time on Tower Gully, a few years ago, with friends Tom and Kris. Although the story has a happy ending it might not have been the case if they had not reached the summit at the same time as an ill-prepared tourist.
Rich says: "The snow was bone hard from the bottom of Observatory Gully, and there were issues with deposits of windslab, so we had to traverse around the higher slopes to get to the bottom of the route. I had to dig a series of ledges so there was some rest for our poor calves. By the time we got to the bottom of the route, our calves were suitably on fire. Then we just had the steep bit left to do – and to avoid a large cornice.
"After topping out, we spotted a guy wandering around aimlessly in the white-out conditions. We saw him make a beeline for the edge of The North Face. I ran to him and grabbed him before it became a fatal day out for him. He was from Hungary and his kit consisted of a furry hood parka, jeans and trainers, and in his tiny rucksack was a bottle of Scotch and a huge cigar to 'celebrate' his first Scottish mountain. I asked him why he was on Ben Nevis and his reply was, 'It is the only one I have heard of'."
The allure of the Ben seems long-lasting for Rich. He says: "The first time I reached the summit I had been inspired because it is the biggest UK mountain. Now, it's my work and I am fortunate to meet lots of interesting people while summiting numerous times. The Ben also keeps me fit – and that fitness allows me to walk other mountains around the UK."
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