60. PlantSea: sustainable seaweed that’s creating a sea change in packaging

Sustainability Award Nominee

In recognition of a sustainability leader that prioritises the health of the planet as part of its company mission.

Startups 100: Sustainability Award

Founders: Rhiannon Rees, Alex Newnes, and Gianmarco Sanfratello
Year founded: 2020
Website: plantsea.co.uk 

While Rhiannon Rees was visiting Bali, she was shocked to discover that the country’s beautiful landscapes were tarnished by plastic pollution. This, along with her beach cleanup experiences, inspired her to make sustainable packaging solutions her mission.

Back in Wales, Rees teamed up with fellow founders Alex Newnes and Gianmarco Sanfratello to kickstart PlantSea, a sustainable packing company that creates biodegradable and compostable packaging solutions made from seaweed and other plant-based materials.

Households in the UK throw away approximately 1.7 billion pieces of plastic packaging every week, which adds up to 90 billion pieces annually. As PlantSea’s products are made from biodegradable materials, these can break down naturally in the environment – reducing the amount of waste that ends up in landfills and oceans.

PlantSea’s mission hasn’t gone unnoticed by investors either, as the company managed to secure an equity investment of £22k from the Development Bank of Wales and other partners, including Sustainable Ventures and SFC Capital.

The business hit another milestone when it secured its first sales, which it attributes to its teamwork and building a supplier and customer network that aligned with its core principles.

PlantSea has high hopes for the future, aiming to manufacture seaweed extract from its bioprocessing facility in North Wales, while also becoming a global leader in seaweed extracts for the world’s leading brands and manufacturers.

With its biodegradable and compostable packaging products, PlantSea is leading the way towards a greener future. And it’s no surprise that as well as featuring on the Startups 100 Index, the company is nominated for the 2025  Startups 100 Sustainability Award.