Large areas of countryside in the South are being opened to ramblers for the first time on Tuesday.
Bill Oddie led a group walk on formerly inaccessible land
The region is the third in the UK to have thousands of acres of private land made accessible to walkers under the Countryside and Rights of Way Act.
The so-called "right to roam" laws were launched at a Bournemouth ceremony followed by a group walk led by TV presenter and birdwatcher Bill Oddie.
Rural affairs minister Alun Michael called it a "very special day".
"Southern England has a wealth of wonderful open countryside which everyone has the right to enjoy," he said.
"The CRoW Act gives everyone the opportunity to do just that but I hope people make the most of it, bearing in mind that it is important to respect the needs of land managers."
The south region is composed of South Gloucestershire, Bristol, Berkshire, part of Somerset, Wiltshire, Hampshire, Dorset and the Isle of Wight.
Any private land considered moor, heath, mountain or downland or registered common land will now be open to walkers.
Ramblers groups have called these maps the most exciting development since the creation of national parks after World War II.
But opponents - including some landowners - say there has been little consultation, decisions on what constitutes open access land have been bizarre in some cases and the appeals process has been time-consuming and costly.
The new laws do not give people a right to roam anywhere. Areas like gardens and cultivated land are not included and there are restrictions on some areas at certain parts of year.
The new freedoms mark a milestone in a decades-long battle
Mr Oddie said: "At last no more straddling barbed wire, limbo-ing under electric fences or being shot at by game keepers - all of which I have experienced in pursuit of wildlife.
"It's wonderful to have access to so many new places, but with freedom comes responsibility. Responsible roaming, that's what it's all about."
The first two areas to be opened up were south-east England and the lower north-west in September.
Nick Barrett, chief executive of the Ramblers Association, said: "For many, the joy of walking is about getting off the beaten track - everybody in this country now has a right to do just that and I hope people will take the opportunity to discover these beautiful areas for themselves.
"I am confident the respect and love walkers have for the countryside will prove that this is a wise, fair and beneficial piece of legislation."