What Is Sustainable Swimwear?

Sustainable swimwear comes down to four things: what the fabric is made from, how it's produced, how long it lasts, and what happens to it once you're done with it.

None of these on their own makes a product sustainable — it's the combination that determines whether a claim holds up or is mostly marketing.

What Actually Makes Swimwear Sustainable?

The word "sustainable" gets used loosely in fashion, and swimwear is no exception. Most conventional swim trunks are made from virgin polyester or nylon, both derived from fossil fuels. Sorting out what separates a genuinely better product from a marketing claim comes down to materials, production practices, durability, and end-of-life.

1. Materials

The foundation of any sustainable swim short is the fabric. Instead of virgin polyester or nylon, sustainable swimwear typically relies on recycled or responsibly sourced inputs, including:

• Recycled polyester (rPET), made from recycled plastic bottles or industrial waste
• Recycled nylon, sourced from discarded fishing nets, production scraps, or other textile waste
• Recovered ocean plastic, collected directly from marine environments rather than from inland waste streams

Some brands are also experimenting with bio-based alternatives — fabrics derived from banana fiber or wood pulp, for example — though these show up more often in beachwear accessories than in the swim short itself. Regardless of the specific material, the underlying test is the same: does it reduce reliance on newly extracted, petroleum-based plastic, and does it hold up to the demands of a swim short — moisture, sun, salt, and repeated wear?

2. How It's Made

Materials are only part of the equation. Ethical production matters just as much: safe working conditions, fair wages, and transparency across the supply chain. On the environmental side, that extends to water conservation, energy-efficient processing, and minimizing chemical use during manufacturing. A brand that can only talk about its fabric — and not the process behind it — is telling half the story.

Small-batch production is one practical way brands reduce their footprint on this front. Producing in smaller runs, rather than mass-manufacturing far in excess of demand, cuts down on unsold inventory and the waste that comes with it — a less visible but still meaningful part of a garment's overall impact.

3. Durability

Lower-cost, trend-driven swimwear is generally built to a lower standard: thinner stitching, less resilient elastic, and dyes that fade faster in sun and salt water. That kind of construction tends to wear out sooner, which means it needs replacing more often — not because the wearer decided to upgrade, but because the seams, elastic, or color gave out first. Sustainable swimwear takes the opposite approach: durable stitching, quality stretch, and fade-resistant color built to hold up across seasons rather than a single trip.

This is one of the more overlooked parts of the sustainability conversation. A pair of swim trunks that lasts three or four seasons instead of one has a lower overall footprint than a cheaper pair replaced every summer, even before factoring in what either pair is made from. Durability and material choice work together, not separately.

4. End-of-Life

What happens to a pair of swim trunks once they're worn out matters too. Recyclable components, take-back programs, and reduced-waste packaging are all part of a more circular approach. Swimwear isn't yet fully compostable at scale, but the direction — designing with an exit plan, not just an entry point — is where the category is heading.

5. Purpose Beyond the Product

Some sustainable swimwear brands also tie their business to a broader environmental mission — ocean cleanup, plastic reduction, or restoration work like seaweed or coral planting. This isn't a requirement for a product to be considered sustainable, but it's a meaningful extension of it: a brand funding restoration work alongside better materials is doing more than minimizing harm.

How Blauw Approaches Sustainability

Blauw's swim trunks are built around two structural choices: what the fabric is made from, and what each sale funds afterward.

Recycled Marine Plastic, Not Landfill Plastic

Blauw's OceanKnit™ fabric is produced in partnership with the SEAQUAL Initiative, which processes marine plastic recovered from oceans, rivers, and coastlines — plastic that's already in the water, not material found near it. That recovered plastic is rebuilt into yarn, then woven into the OceanKnit™ fabric used in every pair of swim trunks. More detail on the sourcing side is covered on the Impact page.

Seaweed Planting With Every Purchase

Every short sold funds the planting of one seaweed plant, through a partnership with the nonprofit Seatrees. Seaweed grows quickly and is widely recognized as one of the fastest-growing natural carbon sinks, while also supporting coastal biodiversity. The full story on how that program works is covered in why we plant seaweed for every short sold.

Built to Last

Lower-durability, trend-driven swimwear tends to need replacing more often simply because it wears out faster — weaker stitching, thinner liners, elastic that gives out after a season. Blauw's swim trunks are built with a tailored 5-inch inseam, a lightweight micro-mesh liner, and salt water and chlorine-resistant construction, designed to hold up to regular wear rather than a single summer.

How to Tell the Difference

If you're evaluating any swimwear brand's sustainability claims, a few questions cut through most of the noise:

• Is the recycled content specific (e.g., recovered ocean plastic, certified rPET) or vague (e.g., "eco-friendly materials")?
• Does the brand explain its production process, or only its fabric?
• Is there evidence the product is built to last, or is it priced and constructed like a single-season item?
• Does any mission-driven claim (like tree or seaweed planting) come with specifics — a named partner, a measurable action — or is it left vague?

Specificity is usually the tell. A brand that names its material source, its manufacturing partner, and its restoration partner is giving you something you can verify. A brand that only uses words like "eco-conscious" without backing them up usually isn't.

Taken together, that's what "sustainable" means at Blauw: material sourced from the ocean itself rather than from around it, a direct restoration program funded by every sale, and a product built to actually last.