The new footwear collection from Spanish fashion brand Ecoalf is made from recycled waste found in oceans and rivers.

Five old plastic bottles sourced from the Mediterranean Sea are used to create each pair of Shao sneakers. This discarded plastic is processed into a yarn, which is used to create a black knitted upper sole that fits the wearer like a sock.

The outer sole is made from a type of algae that grows in excess in lakes and rivers. Ecoalf transforms this algae into a flexible foam that permits easy movement, while benefiting the environment.

"Algae gives us the most flexible-performing foam," the brand told Dezeen. "Also, removing it allows clean water to circulate properly, supports plant and animal life, and eliminates the need for non-renewable oils."

The shoe has a minimal, no-fuss design, meaning it can be mass-produced as efficiently as possible with these limited raw materials.

"The process is zero-waste," said the brand. "We only use two materials, and construct the upper sole in a way that reduces the number of steps in the supply chain to just one. There are no laces, no insole, and we’ve printed our label to avoid using any extra fabric, without compromising on the design."

Ecoalf works with fishermen along the coast of Spain to source the waste for all of its collections, as part of a long-term project called Upcycling the Oceans. The fishermen take rubbish caught in their nets to their local port for Ecoalf to collect and process.

"Once we have the waste, it is classified by category," Ecoalf explained. "We keep the plastic bottles, and the rest goes to a recycling facility. For the plastic, we do a quality control check, because a bottle at the bottom of the ocean is very different to one floating along the coast."

Once it has been thoroughly cleaned, the plastic is broken down into smaller parts and reduced to polymer. Ecoalf uses this raw material to create yarn for a range of different fabrics.

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The programme began in Alicante in 2015 and is now underway in 52 ports, with over 3,000 fishermen involved and 250 tonnes of waste material already removed from the oceans. In 2017, Ecoalf extended the program to Thailand at the request of its government.

The shoes will launch in September 2018, as part of Ecoalf's new Ocean Waste footwear collection

To date, Ecoalf has developed 250 fabrics made from ocean waste, including ground coffee, discarded fishing nets and used tyres. All products are made in Spain and sold in retail stores in Madrid and Berlin.

The brand was founded in 2010 by Spanish entrepreneur Javier Goyeneche, who gave a talk about sustainable fashion at Tech Open Air in Berlin last month.

"The best thing to do is not to keep on using natural resources, but to make a new generation of recycled products, with the same quality and design as non-recycled," he said during the presentation.

Ocean plastic is an increasingly popular material with designers, as the global waste crisis continues to dominate the environmental agenda.

Adidas is one of the biggest brands that has been championing the use of recycled plastic, as part of its long-standing collaboration with environmental initiative Parley for the Oceans. Spanish designer Adolfo Correa also recently joined the cause, by creating a Hawaiian shirt featuring crabs stuck in bottle caps and plastic six-pack rings.

The Shao sneakers are set to launch in September 2018, forming part of Ecoalf's new Ocean Waste footwear collection.