Scotland will lose its outdoor education sector forever without Scottish government funding, the industry has warned.
Outdoor centres across Scotland said ministers had made a “catastrophic” decision not to offer financial support during the pandemic.
School residential trips are not allowed under Covid-19 restrictions.
The Scottish government said it had funded development of guidance for “safe day visits” to centres.
There are about 60 outdoor centres in Scotland, although not all of them offer residential courses.
Spring term at the earliest
The larger residential centres typically offer week-long visits for schoolchildren, with some part-funded by councils and others run by the third sector.
For many centres, the money from residential courses makes up the bulk of their income.
However, guidance issued to local authorities by the Scottish government on 14 August advises against all residential school trips until the 2021 Spring Term at the earliest.
The sector asked for financial support to help it survive, but the request was turned down last week.
An email from an education policy manager for the Scottish government, sent to the heads of outdoor centres across Scotland, said Deputy First Minister John Swinney had considered “possible financial support”.
But the email continues: “I have now received a response from the deputy first minister and unfortunately he is unable to agree financial support for the sector given continued pressure on Scottish government budgets.
“I appreciate this will be extremely disappointing for all of you.”
BBC Scotland understands there are fears that half of all centres in Scotland could close permanently in the next few months.
Martin Davidson, Scotland director at The Outward Bound Trust, said: “This decision is catastrophic for both young people and for outdoor centres.
“The school residential has been a feature of Scottish education for years. It is highly valued by teachers, it develops self-confidence and helps with mental health and wellbeing.”
Mr Davison said the “fabulous experiences” of millions of young people would come to an end without Scottish government support.
He added: “While the government has supported many sectors to ensure their survival and enable them to adapt, residential centres are unable to operate and remain in lockdown.”
A Girlguiding Scotland centre at Nertherurd House near West Linton closed in August with five members of staff made redundant.
The movement said the the impact of the coronavirus pandemic had exacerbated existing financial issues and it was no longer viable to keep it open.
A coalition of Scottish outdoor organisations – including Girlguiding, The Outward Bound Trust and the Association of Heads of Outdoor Education Centres – has warned that “more [centres] will follow and shut down permanently before Christmas”.
The group has launched a “Save Your Outdoor Centres” campaign in a bid to change the Scottish government’s mind about funding.
Jane Campbell Morrison, chairwoman of the Scottish Adventure Activity Forum, said government support for residential centres was “vital”.
“We already work with thousands of teachers every year to help deliver the outcomes related to Curriculum For Excellence,” she said.
“Young people have missed out on so much this year due to lockdown and coronavirus, we cannot let the residential experience be another thing they have to lose.”
Safe day visits
The group said the centres also supported thousands of jobs in rural economies across the country.
A spokesperson for the Scottish government said: “Outdoor education centres can provide young people with a variety of curriculum relevant experiences.
“At present, the increased risk of virus transmission associated with overnight stays means that the Scottish government has advised against school residential visits to centres – risk-assessed day visits are permitted.
“To support outdoor education centres during this challenging time we have funded the development of guidance for schools and outdoor education centres on safe day visits.”