As a maritime nation our prosperity has been linked to the sea for centuries. From Drake to Darwin, our history has been shaped by the voyages over the horizon. We have prided ourselves on ruling the waves – but it has only been in recent years that the fragility of the ocean has become apparent.

Marine plastic, ocean acidification, climate change, overfishing and habitat destruction all mean that the clear blue seas we have marvelled over are not a given for our children. That is why it is this generation that must step up and protect our oceans. The first step to doing that is to value them.

The BBC’s Blue Planet II showed that our obsession and careless disposal of plastic is causing real damage to marine creatures. Far-off coral reefs are being destroyed by the climate crisis and at home fragile ecosystems in our coastal waters are under threat. Britain has a complicated tapestry of marine protected areas, sites of special scientific interest and many more designations. From Plymouth Hoe, the cliff top park that overlooks Plymouth Sound, you can see a fair few of these protected areas, but it is a challenge to find anyone who can name one let alone correctly identify its position.

The last Labour government introduced these marine protections in one of its final acts. But technical protections have not gelled with the public. That is why in 2017 I proposed the creation of a new marine designation: the national marine park. Building on the success of the post-war Labour government’s creation of national parks, the national marine parks will provide a plain English understanding of the myriad protected areas along the coast. The language of a national marine park suddenly, even without prior knowledge of marine protection, creates the impression that these waters are important, valued and protected.

This weekend, two years after the proposal to designate Plymouth Sound as the UK’s first national marine park was included in my 2017 election leaflets, it was finally officially declared. Flanked by Lewis Pugh, the UN Ocean Ambassador and the man who famously swam the English channel from Cornwall to Kent, representatives from industry, charities, commerce, science, research and the Labour-run council signed a declaration making Plymouth Sound a nation first.

The Plymouth Sound National Marine Park covers the world’s third largest natural harbour after San Francisco and Sydney. It includes waters home to 1,000 marine species from sea-grass that sequester more carbon than trees and seahorses found nowhere else, to a variety of fish that would look at home in any tropical reef. It includes waters used by commercial fishers, shipping and ferries – and it covers the sea lanes used by the Royal Navy’s nuclear submarines and warships based at Devonport. In short, the reason Plymouth Sound is the first national marine park is because we have every use of the sea in one location – sustainably managed, protected and home to countless jobs from engineering to science, boat building to amphibious warfare.

Plymouth Sound is the nation’s first national marine park but it will not be the last. Last year, Labour officially backed the roll out of marine parks nationwide as part of our marine policy. As the Shadow DEFRA Minister responsible for all things wet, the journey of the national marine park from election promise to a reality in only two years is humbling. But it cannot stop here. Today, Theresa Villiers, the Conservative Environment Secretary, backed the idea and pledged new funding for this project. It shows the power of a good idea that -despite being proposed by a Labour candidate who defeated a Tory MP – it can still be adopted by a Tory government in the build-up to a fiercely contested general election.

Plymouth’s national marine park allows us to reconnect with the ocean, to value its beauty and majesty, its variety of marine wildlife and the diversity of commercial and military activities on the water and below. Let’s create a second, a third and a fourth. The next Labour government will roll out this concept nationwide from Plymouth to a coast near you. Just as the 1945 Labour government stepped up to the plate to create our National Parks, the 2019 Labour government will roll out a new form of designation for our seas and our coast. Let’s now tell that story and build campaigns to create national marine parks nationwide. The future of these precious and fragile waters is in all our hands. Let’s get to work to value them more.