The roll out of historic right to roam laws across England will be completed on Monday.
Walkers are urged to use the new right responsibly
Walkers will be able to roam 6,250 square miles of mapped areas of heath, mountain, down and common land, much of which used to be off limits.
The move follows a campaign of more than 100 years to allow people to freely walk across mapped access land without sticking to paths.
The access area equates to 7% of England's total land.
The area is equivalent to 1.6 million football pitches.
The east and west of England are the last mapping regions to open in England to complete the implementation of the new right.
Chair of the National Countryside Access Forum Pam Warhurst hailed Monday as "an historic day".
"People can have fun exploring more of England's beautiful and varied landscapes," said Ms Warhurst, who is also deputy chair of the Countryside Agency.
"The Countryside Agency, and the Countryside Commission before it, has worked to increase opportunities for public enjoyment of the countryside for over 50 years and this new right of access is a major landmark in working towards this."
It was important that people used the new right responsibly by following the Countryside Code, she added.
New editions of Ordnance Survey Explorer maps show all access land made available to roam by the new right.
New maps covering the whole of England and Wales are expected to be published by next April.