Hemp bikinis and natural rubber wetsuits: the most sustainable swimwear options for summer

<span>Photograph: davidf/Getty Images</span>
Photograph: davidf/Getty Images

Swimwear is one of the hardest things to make sustainably. There are a few reasons for this: it has to keep its shape when submerged in water, dry quickly afterwards and be able to withstand exposure to salt, sunshine and chlorine, which can all be corrosive. That’s why it’s almost always made from polyester or nylon. These materials are hydrophobic (they don’t absorb moisture) while natural materials are super absorbent and become heavy and misshapen when wet.

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But polyester and nylon are common plastics derived from fossil fuels, which cause a litany of environmental harms. Some brands have turned to materials made from recycled plastic like Repreve (polyester) and Econyl (nylon) to mitigate the problem, but these materials have limitations too. Now sustainable swimwear designers are seeking alternative materials that will withstand playing in the sun and the surf.

Wood-based swimwear

Pyratex Power 3 is a new fabric made from 89% lyocell (a wood-based fibre) and 11% elastane (from petrochemicals). It has been used in swimwear by the US designer Mara Hoffman. Although it is part of the brand’s transition away from fossil fuels-based materials, the presence of elastane means it is not entirely plastic-free, but Hoffman says they are working to improve this. Which is good, since Philippa Grogan, a sustainability expert from Eco-Age, says “elastane will compromise recycling and biodegradation at the end of [the garment’s] useful life”.

Lyocell is made from sustainably sourced wood and using systems that minimise the impacts of the chemicals required to turn a tree into a fabric. But questions remain over how it will perform as a bathing suit.

Rebecca van Amber, a textile scientist from RMIT University, says it’s unclear how durable this material is when exposed to water, sunshine and chlorine. “It would be interesting to see if Pyratex performs as well as polyester and nylon,” she says. “Without seeing performance data, it’s anyone’s guess.”

Hemp swimwear

Los Angeles based swimwear brand Natasha Tonic makes made-to-order swimwear out of hemp-cotton blends. Because their pieces are made from natural fibres, they can perform double duty as underwear or activewear. But hemp is typically used for shirts, trousers and jackets, and is generally absorbent and not particularly fast-drying. So it’s unclear how swimwear made from this material will handle being submerged in water.

A model wears hemp and cotton blend swimsuit by Natasha Tonic on the runway at Miami Swim fashion week.
A model wears a hemp and cotton blend swimsuit by Natasha Tonic on the runway at Miami Swim fashion week. Photograph: Reagan Rule/Getty Images

“Hemp is one of my favourite fibres,” says Grogan. “It can flourish without chemical intervention, it grows fast and with very little water compared to other fibres … I doubt a hemp bikini would be suitable for the Olympics, but perhaps it would be a nice addition for a holiday with lots of sunbathing?”

Synthetics made from plants

Sometimes called bioplastics, the biggest advantage of making polyester out of plants like castor beans or sugar cane (rather than petrochemicals) is reducing our reliance on fossil fuels – but they’re not a perfect solution. Amanda Johnston, a curator and education consultant for the Future Fabrics expo, says “using crops for the new era of bio-based synthetics is not without controversies due to intensive farming methods”, as well as ethical concerns about growing materials rather than food on arable land.

Another key issue is the lack of biodegradability of bioplastic polymers and the resulting microplastic pollution. And since the swimwear made using this material – called Biosculpt – has been blended with 23% spandex, which is a virgin synthetic, Van Amber says it cannot be recycled.

Alternative wetsuits

Wetsuits are typically made from neoprene, a synthetic rubber. “Traditional neoprene is made using non-renewable petroleum – one of the most toxic manufacturing processes there is,” says Johnston. So, innovations in the wetsuit space are very welcome.

One option is a material called Ecoprene that is limestone-based, but according to Johnston, it “does not represent a positive development”. This is due to the impacts of extracting the limestone, also a non-renewable resource, from the earth. Processing the material is chemically intensive and involves extremely high temperatures which uses lots of energy.

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Both petroleum and limestone-based neoprene have significant environmental impacts, says Johnston, “although limestone spills are a lot easier to clean up”.

Another alternative is a natural rubber neoprene called Yulex that is sourced from hevea trees which are harvested and processed in Sri Lanka, using certified, safe chemistry without petroleum solvents. Although the material is blended with 15% synthetic rubber, Johnston says: “Yulex represents a significant improvement in this material category.”

Biodegradable nylon

This material is derived from fossil fuels, but unlike typical plastics which take hundreds of years to biodegrade, this nylon has been designed to allow bacteria to penetrate it under landfill conditions where it breaks down into biomass and biogas. According to Amni Soul Eco this will happen in around five years, in the right type of landfill.

“There are a few things I have an issue with here,” says Grogan. She says the actual biodegradation rates will differ based on the type of landfill the nylon is scrapped in, and that the material has to be disposed of in a very specific way for biodegradation to take place.

Further to this, Van Amber is concerned that biodegradable nylon will produce microfibres at a faster rate. “We already know these are found everywhere on earth, particularly in our oceans, and are having an impact on aquatic life – the extent of which we do not yet fully understand.”

The most sustainable swimsuit

As the innovations currently stand, the most sustainable swimwear is going to be the most durable and long-lasting, says Van Amber. “Until there is an appropriate end of life method for reuse or recycling, the best option is to use your swimsuit for as long as possible,” she says. The best way to extend the life of your swimsuits is to wash them after every wear and keep them out of the sun.