New seasonal by-laws have come into force restricting camping around Loch Lomond and in the Trossachs.
Camping in four management zones in popular areas between March and September will require a permit or booking a campsite pitch.
Loch Lomond and the Trossachs National Park said the move was to protect the area from antisocial behaviour, including littering and fireraising.
Ramblers Scotland say there will not be enough pitches to cope with demand.
The park authority said it had provided more than 300 camping and motorhome places in the new zones.
It said the by-laws cover less than 4% of Loch Lomond and the Trossachs National Park.
The new by-laws, which were approved by the Scottish government last year, follow similar legislation introduced to east Lomondside in 2011.
Those flouting the by-laws face being reported to the procurator fiscal and a potential fine of up to £500.
Loch Lomond and the Trossachs National Park chief executive Gordon Watson said: "Enforcement is very much a last resort if people are unwilling to comply or they are causing unacceptable damage or disturbance in the area.
"If someone puts up a tent, they don't get a criminal record.
"If they're putting up a tent in somewhere that isn't designated for camping, a ranger may approach them and say unfortunately this isn't a place you can camp, but here are all the places you can camp.
"The presence of the by-law means that people know that there is a recourse if they refuse to comply.
"Camping by-laws have been in force since 2011 in east Loch Lomond, I think in only one or two cases has there been a formal report in all that time."
The camping places will be a mix of informal campsites and permit areas. Campers will also be required to bring their own firewood.
Mr Watson said: "Some of the loch shores that are very accessible from public roads are very popular for camping.
"Sometimes that brings quite a lot of problems in terms of repeated camping week after week taking its toll on the environment, but also antisocial and irresponsible behaviour from camping in terms of people littering, chopping down trees for firewood - sometimes having a bit of a party and causing disturbances as well.
"That's something we've seen for many years at Loch Lomond that we feel as a park authority we need to manage."
'Hassle and cost'
Ramblers Scotland said it believed the authority could have addressed those issues by investing in low-cost campsites and enforcing existing laws.
Its director, Brendan Paddy, said he was "disappointed" that the park was going ahead with the plan.
He said: "It undermines Scottish access rights by providing too few tent pitches to cope with demand and by charging to camp in previously free areas.
"Campers often won't get any toilets, drinking water or bins in return and we fear the hassle, cost and insufficient number of permits may put people off visiting this wonderful area."
Mr Paddy said that national parks should aim to attract large numbers of visitors.
He said: "This can cause pressure on individual areas, so we support the park's plan to provide more camping infrastructure, including toilets, bins, etc.
"However, their planned provision of about 300 camping spaces doesn't meet levels of demand from before the by-laws, when up to 800 tents were recorded on busy weekends."