Out the top of St Agnes, a steep village on Cornwall’s north coast, sits a small utopia. The disused mine stack at Wheal Kitty overlooks a group of warehouses reinventing local industry: there is the HQ of the pioneering marine conservation charity Surfers Against Sewage, its big green eye logo staring at zero-waste shop Incredible Bulk. Next door to that is Canteen, a community-minded cafe uniting local people over £5 meals and long trestle tables. Often they are ravenous from a surf or beach clean at Trevaunance Cove down the cliff, a hypersaturated blue on this scorcher of a summer’s day.

Then there are the offices and flagship store of Finisterre, an outdoor apparel company focused on sustainability and functionality. Tom Kay, who founded the business 15 years ago, meets me in the office breakout area. The place has the sweet, salty tang of surfboard wax, and Kay’s dog, Otis, roams around under employees’ desks. Finisterre’s aim, says Kay, part hippy, part focused businessman, is to connect people with the sea. “We believe that they experience better wellbeing, better health, better spirituality, mental space,” he says. Once a week at Finisterre, staff start an hour late so they can participate in Sea Tuesday – getting wet in whatever way floats their boat, board or body. “Hopefully, there comes with that a guardianship, realising the importance of looking after the sea.”

After all, what the sea gives us, we seldom give back. David Attenborough’s Blue Planet II kickstarted a nationwide battle against the single-use plastics clogging the oceans. Surfers have an intimate relationship with the water, but the damage they do goes under-reported. Wetsuits are made of neoprene, a synthetic rubber originally invented to line landfill sites: good for staying warm while surfing in December, less so for the environment. Finisterre estimates 380 tonnes of wetsuit waste ends up dumped every year. Eighteen months ago, Kay decided to do something about it. Wetsuits from Wetsuits is Finisterre’s mission to create the world’s first fully recyclable wetsuit, and to pioneer the means of recycling any old suit.

Finisterre already uses a biodegradable rubber in its suits. It makes clothes from Econyl, a recycled nylon made from discarded fishing nets and carpet tiles. Fully recyclable wetsuits are the next step. “We have an outlook to do something about these problems if we can,” says Kay. “We’re very much involved in solving these problems in innovation.”

Finisterre hired what Kay believes is the world’s only full-time wetsuit recycler to help the company look for sustainability solutions. Jenny Banks is a graduate of the material futures MA at Central Saint Martins in London. Normally, at the start of such a project, she says, you would spend a year reviewing existing research. “But it’s been so hard to find information,” she says. “We’ve got one or two papers on testing wetsuit properties and construction, and a lot of those testing standards are military standards from the 50s when they started making diving suits.”

It is possible that the knowledge is “kept within the walls” of the main suppliers, she says. Or that there has not actually been much wetsuit innovation since the San Diego physicist Hugh Bradner invented them in 1952. “There’s a reason why we still use the materials that we use in nonrecyclable wetsuits today,” says Banks. “They are pretty brilliant.”

Conventional wetsuits can contain as many as 15 different materials that are nearly impossible to separate at the end of a suit’s life. Finisterre’s plan was to design a suit made of a limited number of materials to maximise the quality of rubber and other material that could be recovered in the recycling process. So Banks started chopping up standard suits and testing the constituent parts for stress and durability. “Fabrics are great for meaning the foam doesn’t overstretch, but the fabrics make recycling really hard. That was the starting point of the redesign – asking: how do we still make the foam strong, but make it recyclable?”

One solution was using a “skin finish” – a texturised biodegradable rubber that prevents water from getting trapped in the fabric and chilling the wearer. But it is controversial, and not for its environmental impact. “Skin finishes were used in the 70s and it’s seen as a very retro thing,” says Banks. “There are a few small brands that still use it as a style point – some people love it and some people hate it. You’re balancing style and sustainability …”

Jenny Banks, material scientist at Finisterre. Photograph: Chetwode & Charles/The Guardian

But the prototype that Kay shows me at Finisterre’s office looks sharp: the skin finish appears technical in an on-trend way. It is a men’s suit because women’s are harder to cut. He has tested it out in the water and, even designed as a 3mm-thick summer suit, it is a bit warm, and not that easy to get on and off. He has me stick an arm down a sleeve, which is sticky – removing a wetsuit at the best of times can be a pretty undignified battle. Still: “This is the most recyclable suit out there in the world, pretty much,” Kay says proudly. “It’s got no laminate on it, you can take the stitching out and then the theory is that it can be totally recycled.”

There is still a lot more testing to go – next, Kay and other testers will wear the suit with temperature sensors for a more precise assessment of the heat situation.

This is the “upstream” element of Wetsuits from Wetsuits: the creation of a product that can be recycled. “Downstream is when the product has gone through the hands of the customer and is about to go to landfill,” says Kay. Here is where another, chemical recycling process comes in. Kay discovered UK company ReNew ELP, whose hydrothermal test plant in Australia uses catalytic thermo-hydrolysis to break down any old wetsuits and marine waste from Sydney’s beaches into a bio-crude. When Finisterre put out a call for old suits to send to Australia, it got 100 in two days.

Banks admits that this discovery may make Finisterre’s recyclable wetsuit seem redundant. But the more materials go into the bio-crude, the more that need distilling afterwards, which is expensive. “By simplifying the materials within our suit,” she says, “we maximise the amount of good quality, pure material we can recover and reintroduce into our wetsuit manufacturing.”

Obviously, these processes also have an environmental impact. “We’re trying to find a partner to do a life-cycle assessment to find out what the balance is between the environmental impact of the recycling and the environmental impact of making them from virgin,” says Banks.

By talking about this, Finisterre is giving away the company secrets. But that is the point. Other surf brands “won’t do it because it’s a nice thing to do, or the right thing to do,” says Kay. “But they will do it when you can prove an economic case. The innovation around the future of business growth has to be waste as a resource. If you can prove that you can get the bio-crude out of the plant in Australia, and that’s saving half of the raw material cost at the start, suddenly there’s an economic argument for it. If we as a brand could prove that change is possible, that’s something I’m really excited about, and really gunning for.”

Wetsuits from Wetsuits was initially conceived and funded as a two-year programme, which would theoretically end in November, but Banks says it is realistically a five-year plan that needs support from the big guns. “At the end of these two years, it’ll be about presenting the prototype, the information from our wetsuit testers and the lab, and saying, this is totally feasible, let’s do this together. We’re a tiny brand in the whole scheme of the wetsuit industry. The next phase would be about partnership and collaboration, and building up enough momentum from the wetsuit industry to put pressure on the supplier to make that change.”

Finisterre is not yet profiting from the programme, and once it hits the market it will have to persuade customers to spend more. Kay notes the growing awareness around the climate emergency, but says he does not think most people will splash out on sustainability. “So that’s the challenge: getting proof of concept, testing this first recycled wetsuit out, and then starting to think about the economic viability.”

It has taken longer than Kay and Banks thought it would to get here, but both sound irrepressibly enthused about what is still to come.

“We could have waited for one of the bigger wetsuit brands to figure this all out, but we didn’t, which I think is testament to how dedicated we are to our ethos of looking after our environment and bringing about positive change,” says Banks. At any rate: the joy of surfing lies in never tiring of the pursuit of perfection, so their temperaments are well suited to their mission.