Outerknown has unveiled its first-ever seaweed-based garment made from Keel Labs’ Kelsun fiber, blending sustainability and style into the iconic Blanket Shirt.
Sustainable materials manufacturer Keel Labs has teamed up with California-based apparel brand Outerknown to launch the first commercial garment made from Kelsun, a seaweed-based fiber. This limited-edition release reimagines Outerknown’s iconic Blanket Shirt, blending organic cotton with Kelsun, marking a pivotal moment for both brands as they push the boundaries of sustainable fashion.
Kelsun is a biodegradable fiber derived from seaweed, offering a viable alternative to conventional textiles that rely heavily on water and pesticides. With the fashion industry producing an estimated 21 billion tons of textile waste annually, Keel Labs says this innovation holds significant potential to mitigate the environmental impact of traditional garment production. It sources seaweed under strict sustainability guidelines, and the fiber it yields is not only bio-based but also biodegradable in wastewater.
Keel Labs, founded by Tessa Callaghan and Aleksandra Gosiewski, aims to revolutionize the textile industry by creating climate-conscious material solutions. Earlier this year, Keel Labs partnered with activist Aditi Mayer on the release of its first t-shirt made from seaweed. It also partnered with Mr. Bailey, crafting the Starboard Vest from the seaweed fiber.
“At Keel Labs, we are deeply committed to our mission of harnessing the potential of our oceans to create better products for people and the planet alike,” Callaghan said, noting that Outerknown shares a dedication to creating a better world.
Every year, up to 500,000 tonnes of microplastics from textiles pollute the world’s oceans, wreaking havoc on marine life, ecosystems, and even human health. Meanwhile, the environmental cost of conventional cotton remains staggering — occupying 2.5 percent of the planet’s arable land while guzzling 16 percent of all pesticide use, putting both farmers and the environment at risk. Seaweed functions much like trees on land by absorbing carbon dioxide from the oceans. As one of the most regenerative organisms on the planet, seaweed thrives solely on the renewable resources of the oceans.
Keel Labs’ innovative approach to harvesting seaweed is built on clean, non-toxic processes that drastically minimize environmental harm while maximizing positive ecological impact. With Kelsun, the company’s seaweed-derived fiber, the numbers speak for themselves: it uses zero pesticides and requires 70 times less water than conventional cotton. Kelsun is also highly compostable, breaking down in just 61 days, enhancing ecosystem health and making a compelling case for seaweed as the future of sustainable textiles.
Once harvested, Keel Labs’ seaweed undergoes an extraction process to isolate a biopolymer, which is then processed into Kelsun fibers. The newly released Kelsun Blanket Shirt retains the timeless look and feel of Outerknown’s organic cotton predecessor but adds a groundbreaking sustainability layer through its bio-based construction.
Outerknown, founded by professional surfer Kelly Slater and creative director John Moore, has consistently championed sustainability, using 99 percent preferred fibers in its collections, including organic, regenerative, recycled, and now bio-based materials like Kelsun. The launch of the Kelsun Blanket Shirt is a testament to the brand’s ongoing commitment to responsible sourcing.
“The Blanket Shirt was one of the first products in our line, and it remains one of my favorite pieces,” Slater said in a statement. According to Slater, it was important to design and build a shirt that was high quality, made from sustainable materials, but felt vintage soft. “We could feel the universal love for the Blanket Shirt from the start,” Slater said, noting that it’s been ten years since the first Blanket Shirt was made. “[W]e are proud to be partnering with Keel Labs on the next generation of this shirt,” Slater said.
Callaghan called the launch a pivotal moment, not just for Keel Labs, “but for the industry as a whole, standing as a marker for what lies ahead when conviction, action, and collaboration combine,” she said, calling the garment the first, but not last, of its kind.
“Working with suppliers that share our love for the ocean is a great fit for Outerknown,” Slater said. “I’m excited to see this grow.”
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