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Underwater Kelp Cardigan

Name: Underwater Kelp Cardigan
Brand: Vollebak
SKU: SWH115OFWXSM
Price: 745.00 GBP
Availability: InStock

An undyed cardigan made from giant underwater kelp forests.

$745

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XXL

Model is 6ft 1 / 187cm with a 38 inch / 96cm chest, and wears size Large.

Built with seaweed-derived Kelsun® fibre
Blended with long-staple Pima cotton for strength and softness
7-ply tuck-stitch knit for texture and weight
Riri metal zip with matte silver hardware
Undyed to preserve the fibre’s natural colour and character
Manufactured in the UK

The ocean grows enormous fields of seaweed that don’t need soil, irrigation, pesticides or fertiliser. All they need is sunlight, saltwater and dissolved nutrients and can grow up to 24 inches in a day. That mix of low maintenance and hyper growth might make seaweed the most important raw material on the planet.

For most of human history, everything we wore came from one of three places, plants, animals, and then oil. From animal pelts to cotton fields, sheep farms, and fossil fuels. Seaweed could be the next place we look.

Seaweed is marine algae and inside its cell walls are biopolymers that can be extracted, spun and knitted into textiles that feel and work like natural fibres. But they’re far less bother. We’re talking around 70 times less water consumption than cotton, zero microplastic pollution, and complete biodegradation within days.

So we blended a seaweed-derived fibre with Pima cotton, sent it to one of Britain’s best knitwear mills, and turned it into a classic long-sleeve cardigan.

Technical details

70% Pima cotton, 30% Kelsun® fibre (alginate)

7-ply tuck-stitch knit

2x2 rib cuffs and hem

Set-in sleeve construction

Pre-shaped collar

Riri one-way metal zip with matte silver puller, slider and teeth

Undyed

Cool hand wash with similar colours

Made in the UK

70% Pima cotton, 30% Kelsun® fibre (alginate)

7-ply tuck-stitch knit

2x2 rib cuffs and hem

Set-in sleeve construction

Pre-shaped collar

Riri one-way metal zip with matte silver puller, slider and teeth

Undyed

Cool hand wash with similar colours

Made in the UK

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Seaweed is the most underrated raw material on the planet.

For the last few thousand years, pretty much everything we’ve worn has come from one of three places: plants, animals, or oil. Cotton fields, sheep farms, fossil fuels. But there’s a fourth option that’s been sitting in plain sight. Seaweed can be grown offshore in simple rope systems, soaking up sunlight and carbon while getting all the nutrients it needs from the ocean. Unlike cotton, it doesn’t take up farmland. Unlike synthetics, it doesn’t start life as oil. You can grow fibres at sea and spin them into pretty much anything you currently make with cotton or polyester. And we did.

Low maintenance and hyper growth make seaweed the raw material of the future.

It grows like crazy and doesn’t ask for much

Seaweeds are packed with polysaccharides – complex sugar-chain molecules like alginate, carrageenan and cellulose. These are the building blocks you need to make biopolymers and fibres. The stuff you can make clothes from. And unlike above-water crops, seaweed farming doesn’t require arable land, irrigation, pesticides or synthetic fertilisers. No soil degradation, no fertiliser runoff, no biodiversity loss. Some species grow up to 24 inches a day. Just in case you’re wondering, that’s one of the fastest growth rates of any organism on the planet.

Seaweed-derived materials biodegrade once you’ve stopped loving them

Seaweed also absorbs carbon dioxide as it grows, acting as a coastal carbon sink, and can integrate with existing marine farming, improving water quality and providing a habitat for other sea creatures. Because it’s entirely biological rather than petrochemical, seaweed-derived materials don’t shed microplastics. And once you’re done with them, they biodegrade in days rather than hang around decades.

Seaweed can grow 24 inches a day with no chemical help.

We worked with a biomaterials pioneer

Kelsun® fibre was developed by Keel Labs, a North Carolina-based biomaterials startup founded with a simple premise. The ocean can grow vast amounts of fast, renewable biomaterial and doesn’t need freshwater or chemicals. And it would solve a lot of problems if we used it to make clothes. The company spent years refining how to extract alginate from kelp and wet-spin it into fibres that behave like conventional yarns and can be used by fibre mills immediately.

From kelp forests to fibre

The Kelsun® fibre we use starts as a seaweed-derived biopolymer. It’s dissolved into a viscous liquid and pushed through microscopic spinnerets, tiny nozzles that turn liquid into thousands of fine filaments. These filaments are set in a wet-spinning bath, then washed, dried and cut into staple fibres that look and behave just like conventional natural yarns. The end result is a spinnable fibre that works on standard knitting machinery.

A plug-and-play material

Most revolutionary textiles play havoc with manufacturing and supply chains. They require new chemistry, processes and looms. Kelsun® was designed differently. It’s what its makers call plug-and-play, a biomaterial that drops directly and easily into existing spinning and knitting systems. Mills can work with it like cotton or wool. That matters because to make lasting change, you need to invent something new and better that slots easily into existing ways of working and making.

It is now being used in biomaterials that could replace cotton and synthetics.

Why we blend it with Pima cotton

Like any new technology, seaweed-derived fibres are still on a journey. And for now, they work best when combined with something tried and tested. We blend 30% Kelsun® fibre with 70% Pima, one of the finest and most durable cottons available. It’s prized for its extra-long staple fibres, which produce a smoother but stronger yarn than standard cotton. Together they spin into a yarn that is strong enough for knitting but with a more textured feel than Pima alone.

Soft where it matters

The alginate-based fibre has a silk-like softness, while Pima cotton adds resilience and breathability. Together they manage moisture well and stay comfortable all day. There’s no crispness or synthetic sheen, no weird feel to the fabric, just the familiarity of a well-made knit. If a material is actually going to upend old systems, it has to be better, and feel better, not stranger.

Built at 7-ply with a tuck stitch

The Underwater Kelp Cardigan is built using a tuck stitch that creates a dense, dimensional surface with real depth and texture. We use a 7-ply yarn, made by twisting seven individual strands together so they share the load. That makes the yarn stronger and more resistant to abrasion than lower ply counts. The multiple plies also smooth out irregularities, producing a more even yarn that gives crisp stitch definition, especially in textured knits like this one. Combined with a tuck stitch that forms small, interlocking loops trapping air between layers, the result is a chunky knit with natural insulation, weight and serious structure that holds its shape wear after wear.

A zip-through designed to layer

The Underwater Kelp Cardigan is a zip-through with a pre-shaped collar that sits flat and clean whether worn open or zipped up. The centre front closes with a one-way Riri metal zip in matte silver, set behind a double welt sandwich trim for a precise, finished edge. Set-in sleeves give the shoulders a tailored line, while 2x2 rib at the cuffs and hem creates tension where you need it, trapping warmth and maintaining the cardigan’s shape over time.

People can use seaweed-derived fibres just like we use cotton and wool.

Knitwear, but from the future

At a distance, the Underwater Kelp Cardigan is an expertly made zip-through in a chunky tuck stitch. Under a microscope, it’s marine biology, advanced polymer chemistry and modern knitting engineering. It’s kelp forests, wet-spinning baths and Riri hardware, all working together to create something comfortable and wearable. The future doesn’t always have to look or feel futuristic. Sometimes it just looks like your favourite cardigan, built from the material of the future.