Tens of thousands of people take on the Three Peaks Challenge each year, when they try to conquer the highest mountains in Scotland, England and Wales within 24 hours.
However, there have been concerns about the impact of so many climbers on Ben Nevis, Scafell Pike and Snowdon.
Among the environmental problems reported have been hillsides scarred by hikers, streams polluted with human waste and residents' sleep disturbed by vehicles at night.
There are fears that teams regularly break speed limits as they drive from one mountain to another, and make walks miserable for other hikers on the mountains by charging past in large groups – often hundreds at once.
Now the Institute of Fundraising has drawn up a new code of conduct for walkers, which it has put out for consultation, to try to tackle the concerns.
The code calls for groups to be limited to 200 people, and for teams of 12 or more to register at least a year in advance.
Minibuses rather than buses should be used, and competitors should avoid residential areas between midnight and 5am, according to the code.
Andrew Campbell, head of land management at wild land charity the John Muir Trust, which owns Ben Nevis, welcomed the new code.
"The main issues have been around the numbers of people going up to the top of the mountain," he said.
"The upkeep of the path at the summit has been an issue. There is also the litter that goes along with large numbers of people, and human waste is quite a big issue as well."
He added that it was important that walkers had a sense of being in a wild area when they went to Ben Nevis.
"The last thing you expect when you are up there is several hundred other people running past you one way and then running back the other direction," he said. "It's not quite the Royal Mile but it's similar."
And he highlighted that although huge sums were raised for charity, very little of the money went to local causes or to environmental issues.
There have been claims that during an average June alone, more than 25,000 people have attempted the challenge.
Gregor McNie, Scotland Manager for the Institute of Fundraising, said: "Three Peaks events are increasingly popular and generate huge sums for a range of good causes, but this must be balanced with resulting pressures on the environment.
"We are delighted that we are able to hold a strong debate amongst all parties on how this balance can be found."
The consultation closes on 19 February.
Register groups of 12 or more people with the Glen Nevis Visitor Centre at least 12 months in advance.
Limit numbers to no more than 200.
Avoid peak holiday times, such as bank holidays and summer solstice.
Discourage racing between teams on and between mountains.
Exclude the driving time between mountains as part of the 24 hour challenge, to avoid speeding.
Do not arrive to start the climb between midnight and 5am when residents live nearby.
Stick to minibuses.
Try to reduce the carbon footprint of the event.
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