Cascais, Portugal

38.706684, -9.488131

Restoring Portugal’s Forgotten Forests

Kelp forests used to be abundant along the coastline of Cascais but have largely disappeared in the last thirty to forty years. This project restores and protects approximately 27,000 sq-ft of kelp forest off the shallow coast of Cascais, Portugal. With the help of project partners SeaForester and the local community, SeaTrees will support this innovative kelp forest restoration project by building a kelp nursery that will allow us to test a new method called ‘green gravel’ with the potential for large-scale marine reforestation.

A fragile ecosystem

Kelp forests historically occurred across all Portuguese rocky shores, but have experienced a dramatic decline due to poor water quality, negative fishing impacts, pollution and coastal runoff. 

Kelp decline in Portugal has led to a decrease in biodiversity, fewer fish, less carbon sequestration and poorer water quality. Local communities that rely on these habitats for subsistence and various economic activities are the ones most affected by their decline.

Today, pollution levels and water quality have improved due to better wastewater treatment and limitations on fishing equipment, yet seaweed has failed to recolonize much of the available habitat, and specific restoration actions to re-seed reefs are urgently needed. Now that conditions are stable for kelp regrowth, we will be implementing innovative seaforestation techniques with project partners SeaForester. 

Scaling up kelp forest restoration

The seaforestation technique used in this project involves the seeding of small stones with seaweed spores, growing them on land in specialized nurseries and deploying them in the sea. The seeded stones can be scattered from a boat without the need for divers or technical equipment, providing a low-cost and scalable seaforestation solution. We have been testing and promoting the technique through research projects in Portugal and overseas.

project partner

About SeaForester

Learn More

SeaForester supports local communities by bringing together stakeholders to plan and implement seaforestation projects to seize the vast potential of seaweed forests in supporting ocean health and livelihoods.

Additionally, they raise awareness and generate public support for seaforestation projects by bringing the public closer to the world of seaweed and making them appreciate these impressive underwater forests.


Sustainable Development

This project provides long-term employment for the local community. This in turn drives other Sustainable Development benefits.

* Thanks to the support of our generous brand partners, this project has been fully funded. If you'd like to support one of our other great projects, send an email to and let us know what lights you up the most!