When you think of Formentera, your mind likely conjures images of powder-white beaches and a turquoise sea so clear it looks like a natural swimming pool. But what lies behind this paradise? What keeps these waters so pristine and this ecosystem so uniquely vibrant?

The answer lies just beneath the surface: Posidonia oceanica. Not an algae, as many believe, but a flowering marine plant that forms vast underwater meadows — a biological treasure that is now under serious threat.

 What is Posidonia? The Lungs of the Mediterranean

The Posidonia meadow between Ibiza and Formentera is an ancient living organism so vital that it was declared a UNESCO World Heritage Site in 1999. This remarkable plant, with roots, stems, and leaves, plays a crucial role in marine health:

• It produces vast amounts of oxygen
• Absorbs carbon dioxide
• Acts as a natural filter, trapping sediments and impurities

Thanks to Posidonia, Formentera’s waters remain crystal-clear — the shimmering icon of the Mediterranean.

 A Submerged Treasure: Biodiversity & Coastal Protection

Beyond its role in water clarity, Posidonia is a cradle of marine biodiversity. Its meadows provide shelter, food, and spawning grounds for hundreds of species — fish, mollusks, crustaceans. Without it, the entire marine ecosystem would unravel.

It also protects the coastline. In winter, dead leaves accumulate on the shore to form "banquettes" — natural barriers that absorb wave energy and prevent beach erosion. Removing them for aesthetic reasons can cause irreversible coastal damage.

The Greatest Threat: Unregulated Anchoring

This invaluable ecosystem is incredibly fragile. Its greatest enemy? Irresponsible boat anchoring.

Every time an anchor is dropped carelessly onto the seabed, it tears through the Posidonia meadows — destroying plants that take centuries to grow. Even the anchor chains, dragged by currents, can devastate entire patches of this habitat.

With boating tourism on the rise, the pressure on this ecosystem has become unsustainable. Add in pollution and climate change, and the Posidonia’s survival is at serious risk.

What Can We Do? Become Guardians of Formentera’s Sea

Losing Posidonia would be an ecological and economic disaster. It would mean saying goodbye to the transparent waters and natural beauty that make Formentera one-of-a-kind.

But here’s the good news: We can all help.

• If you're sailing, use the eco-friendly mooring buoys (gavitels) provided, or anchor only in sandy areas — easily recognizable by their light color.
• As a tourist, educate yourself, respect the environment, and share the message.
• Support sustainable tourism and local conservation efforts.

Protecting Posidonia is not just an ecological act — it’s a gesture of love for Formentera’s future.

Sustainable Anchoring in Formentera: A Guide to Mooring Buoys

In Formentera, mooring buoys (gavitels) are placed in various bays to prevent anchor damage to the Posidonia meadows. Anchoring is prohibited in many areas of the island to protect this fragile marine plant.

Using these buoys is not just responsible — it’s required by regulation.

Where to Find the Buoy Fields

Regulated mooring zones are found in some of the island’s most iconic spots:

• Espalmador: In the stunning bay of S’Alga, managed by Balears Life Posidonia
• Ses Salines: This protected area also has several mooring options
• Caló de s’Oli: Another bay offering eco-friendly anchoring
• La Savina Port: The island’s main port includes two marinas — Marina de Formentera and Marina La Savina

Why Use Mooring Buoys?

Choosing a buoy isn’t just about following the rules — it’s about actively protecting Formentera’s marine life. Irresponsible anchoring has caused severe damage to Posidonia meadows, which:

• Produce oxygen
• Prevent beach erosion
• Serve as habitats for marine species

Anchoring responsibly means enjoying the island’s beauty sustainably, ensuring it remains pristine for generations to come.

Local Projects Supporting Posidonia Conservation

Save Posidonia Project

Launched by the Formentera Island Council in 2017, this project invites people to “adopt” square meters of Posidonia. Over 245,000 m² have been sponsored to date.

 Vellmarí Association

With over 30 years of experience, this local NGO works on marine conservation and partners with initiatives like Smart Green Seas, which includes underwater nurseries to regenerate meadows between Ibiza and Formentera.

 GEN-GOB / “La Mar” Project

A Balearic environmental group that collaborates on awareness campaigns, marine policy forums, and scientific roundtables under the Save Posidonia Forum.

Final Thoughts

Formentera would not be the same without its underwater blue heart. Posidonia means life, oxygen, clarity, protection, and biodiversity. Caring for it is our collective duty — as visitors, sailors, and ocean lovers.

Sail with care. Stay informed. Take action. The future of Formentera starts beneath the surface.