With their snow-capped peaks and the lure of stunning views, thousands of hillwalkers and climbers are set to descend on Scotland’s mountains this May Bank Holiday.

However, despite their tranquil appearance, Scotland’s mountains are deadly. Recent weeks have seen a spate of cases in which inexperienced, ill-equipped or foolhardy hillwalkers have put themselves and rescuers in danger on our mountains.

And with latest information from Scottish Mountain Rescue revealing that 26 people died on our hills in 2014, with rescues totalling a massive 533, it is clear hillwalking is not to be taken lightly.

That is why, with temperatures forecast to dip to -3C, with a possible wind chill factor of -20C, Lochaber and Skye Police are warning hillgoers to “be prepared not rescued” as they venture out into the mountains this weekend.

Last weekend, a 23-year-old hillwalker had to be rescued from Bla Bheinn on Skye after he embarked on the mountain climb with nothing but the GPS on his (out-of-battery) phone with which to navigate. It was, the helicopter rescue crew said, “entirely avoidable”.

“Google maps on a phone with no charge, no map and a hopeful attitude are no mix for hills on Skye (or anywhere!),” Lochaber and Skye Police tweeted after the rescue.

“Be prepared not rescued.”

A month ago, Sarah Albone, 28, hit the news after she was found disoriented on snowy Ben Nevis wearing shorts and carrying only a selfie stick.

Stories like these are the tip of the iceberg. The Sunday Herald spoke to some of the busiest mountain rescue teams across the country who described regular call-outs from people who had no map or compass; lost hikers climbing with only paper print-outs of internet maps that disintegrated in the rain; walkers who had been reliant for navigation on mobile phones that have rapidly lost charge; and incidences of hypothermia because of inappropriate dress. Heather Morning, mountain safety adviser for Mountaineering Scotland, even described witnessing a walker wearing stiletto boots on the Cairngorm plateau. That walker did not, however, call for rescue.

Andy Rockall, general manager of Scottish Mountain Rescue said: “That phrase, ‘Be prepared, not rescued’, has been on social media over the last few days. It’s apt. Be safe out there. And if things are looking bad, don’t be scared to turn around and come back. The mountain’s going to be there tomorrow. There’s no shame in changing your plans.”

This weekend, in other words, may not be the time to take on some challenging peak, unless you know what you’re doing with crampons and a pair of ice axes. And it’s never the right time to take on a mountain with only the GPS on your phone for navigation. “Map and compass” is the mantra from all rescue teams.

According to Rockall, this is usually one of the biggest weeks of the year on the mountains. “We will get people travelling huge distances to be here this weekend,” he said, “and right now outside my window it’s snowing quite heavily. People travel long distances to get here. So it’s not just about changing your plans when you’re on a mountain, it’s also about altering them when you get to the bottom of the mountain and it’s covered in white stuff and you’re kitted out for summer.”

Heather Morning agrees, stating: “There will be a lot of people who have planned to walk up Ben Nevis this weekend, who perhaps even are part of big charity events, and some May bank holidays it would be a relatively straightforward climb,” she said. “But Over this weekend, climbing Ben Nevis is going to be a serious undertaking that requires specialist equipment, knowledge and skills. If people are planning to go high, then they’re going to encounter hard, icy snow, and they’re going to need specialist winter kit like rigid boots, axes and crampons.”

A day out in the hills, she pointed out, doesn’t always have to be about determinedly conquering the very highest peaks.

Almost every year brings death on the mountains. The first four months of 2016 have brought a series of tragic losses. Rachel Slater and Tim Newton were experienced climbers who went up Ben Nevis on Valentine’s Day and never returned. Two elderly men died of hypothermia after setting out for a walk in Dumfries and Galloway. And another climber died in February after being caught in an avalanche. Peter Nielsen, an experienced mountaineer, fell while tackling, unroped, the snow ice climb of Aladdin’s Buttress. Nielsen fell over the top of a mountain rescue team member who immediately called the police and his team, then descended to help, but the climber was too badly injured after having fallen 400ft. Even the most experienced, best-equipped people have accidents.

The number of calls to mountain rescue teams has increased dramatically over the last 50 years, from less than 60 per year in the 1960s to more than 500 per year now. Gerry Akroyd, team leader at Skye Mountain Rescue, observed that he had 66 call-outs in the last year. Lochaber Mountain Rescue has dealt with 133 incidents this year, a massive leap according to team secretary Miller Harris. In the 1980s, there were around 30 to 40 per year.

“It’s gradually increased as time has gone on,” said Harris. “More people have leisure time. A lot more people are going onto the hills. A lot of people are doing charitable walks.”

Scottish Mountain Rescue’s Andy Rockall said technology may also have an impact on the number of calls. “Teams across the country get called out on occasions when they wouldn’t have previously. Say it gets dark and somebody with a mobile phone starts to think they need help, they call for help and we go and help them. In the past they would have just sat behind a rock, spent the night, and in the daylight they might have seen where they were and just walked off.”

The people who provide this service are volunteers, often climbers and mountaineers themselves, who love the mountains and want to offer others the kind of service they’d like to be able to call on should ever they find themselves in serious difficulty. But the system is under strain, according to Harris of the Lochaber team, who has called for walkers and climbers to donate to Mountain Rescue.

It would, he said, offer good value.

“Our team alone must be saving the public purse millions,” he said. “In other countries, like France or Switzerland, that cost would come out of the public purse.”

For the teams that go out to rescue people there is also risk from avalanche or extreme weather conditions. Willie Ross of the Cairngorm team recalled: “There have been a few occasions where I’ve found myself on snow slopes in the middle of the night when I’ve thought to myself, ‘I shouldn’t really be here. You get a feel for a snow slope when you’re on it, if you think it’s safe or is it likely to avalanche. You can hear the sound of it as you walk.”

Reliance on technology is one of the commonest avoidable mistakes people make. Akroyd of the Skye team that rescued the climber from Bla Bheinn said: “They don’t seem to realise that mobile phones aren’t the panacea. You need map and compass if you’re going on any mountain anywhere on Skye, and you need to know how to use them. People think they can go anywhere in the world now with their phones. But they’re in a mess when the signal goes blank, which it does in certain coires up here. It’s too late then. And with these mechanical devices, the batteries run out quickly.”

Part of the problem, he believes, is that the younger generation are not so educated in the skills, which are not always taught in schools.

“I would be very interested to find out what percentage of younger climbers and hillgoers actually know how to use a map and compass,” agreed Ross of the Cairngorm Mountain Rescue team.

“I’d like to be proved wrong. But I suspect that a far greater percentage are not totally competent as that age group might have been 20 years ago.”

Another problem, said Akroyd, is that many people don’t do enough research. “They’ve seen something in a film or on television and think they’ll go there and do that. The prime example is people who think Danny Macaskill can ride his bike on the Cuillins [as he did in the film, The Ridge]. They think if you can ride a bike, you can walk on it. But you can’t. The perception is totally wrong.”

The mountains are there for all of us to be enjoyed: rescue teams agree on this. But this weekend is one of those times when caution is urged. Crampons not stilettos. Map and compass as well as phone. And lower peaks, rather than high ones, if you don’t have the experience.

“It’s definitely winter,” said Heather Morning. “We all need to be aware of that and perhaps modify our plans and enjoy a lower hill.”