Government agency Natural England says it is now officially working on the whole length of the planned England Coast Path.
When complete, the 4,345km (2,700-mile) route will enable walkers to access the entire English coastline.
Natural England said it had reached the milestone on its way to the expected completion date of 2020.
The agency’s chairman Andrew Sells said: “We are now working on all sections of our beautiful and varied coastline so the ability to walk the longest, continuous coastal walking route in the world is on the horizon.
“I’m extremely proud of the strides we have taken to reach this point. We will continue to work closely with landowners, communities and local authorities to create the best possible route, to bring more people closer to nature, and benefit local economies.”
So far Natural England has opened just over 300 miles of coastline, enabling thousands of people access England’s coastal scenery.
The new routes link up the best existing coastal paths, create new ones where there were none and in some cases move paths nearer the sea so walkers have a better opportunity to properly enjoy the country’s coastal views and beaches.
Most recently, routes have opened in North Yorkshire and Norfolk, with further stretches set to open in Kent, the north east and Cumbria over the coming months.
Rural affairs minister Lord Gardiner said: “We have some of the most spectacular coastland in the world, with iconic sites such as the White Cliffs at Dover and the picturesque beaches at Whitby attracting millions of tourists and walkers every year.
“The England Coast Path is a hugely significant project – helping people across the country to access our stunning coastline and providing a significant boost to the economy of our coastal communities.
“By working closely with landowners, farmers and local communities, we are well on track to creating the world’s longest coastal path by 2020.”
The south-west stretch is already worth £400m to the economy. Natural England says by offering new and approved access to some of the country’s best tourist hotspots, the England Coast Path will bring a huge boost to tourism – an industry already worth £106bn.
Alongside the already opened routes, a further 621km (386 miles), including the first stretches in Lincolnshire, Essex and Exmoor have also been proposed. Natural England said it is now working with landowners and others to look at where the route would go on all the remaining sections.
The England Coastal Path is the result of the Marine and Coastal Access Act, which was passed by the last Labour government in 2009. It followed the Countryside and Rights of Way Act which introduced a limited right to roam in England and Wales.