Posidonia Anchoring Rules: What Cruisers Need to Know in 2025

If you’ve sailed the Mediterranean, you’ve probably heard someone talk about Posidonia. Maybe a patrol boat told you to move your anchor, or maybe you’ve noticed the signs in bays around Spain or France.

Posidonia isn’t seaweed—it’s a flowering plant, a seagrass that grows in big underwater meadows. They’re sometimes called the “lungs of the Mediterranean” because they produce so much oxygen and shelter so much marine life.

The problem is that anchors damage these meadows badly, and they take decades to grow back. That’s why in 2025 you’ll see more and more Posidonia anchoring rules across the Med. It’s becoming part of daily cruising life.

Why It Matters

When I first started living aboard in Med, I always chose sand for my anchor. Sand holds better, and I knew it kept the boat safer. Later, I learned how important that choice was for the sea too—because those dark patches in the water are living meadows, not just weeds. Realizing this made me even more careful and respectful of where I dropped anchor.

Posidonia meadows keep beaches from eroding, give fish a safe nursery, and even help with climate change by storing carbon. Drop an anchor there, and you rip up roots that have been growing for hundreds of years. That’s why many countries have started protecting them seriously.

How Rules Are Changing in 2025

In Spain’s Balearic Islands, the patrols are already very strict. If you anchor on Posidonia in Ibiza or Formentera, there’s a good chance someone will ask you to move, and fines are possible. France is going the same way. Along the Côte d’Azur and in Corsica, there are now zones where anchoring is not allowed, and more eco-moorings are being added each season.

Greece is a little slower, but the trend is clear. In Natura 2000 sites, anchoring restrictions are already in place, and I’ve started to see eco-moorings in bays that were once free for everyone. It’s not yet as tightly controlled as Spain, but we’re heading there. By 2030, the plan is to have eco-moorings available for boats under 24 meters all across the Med.

Spotting Posidonia in the Water

The first step is simply knowing what you’re looking at. From the deck, sand shows up as bright turquoise, while Posidonia looks darker—green or brown. Once you train your eye, you can tell at a glance. And today there are apps like Donia or Navily that even map the meadows, which makes it easier to plan where to drop.

Eco-Moorings and the Future of Anchoring

Instead of throwing down an anchor, eco-moorings let you tie up to a buoy that’s fixed with a system that doesn’t tear up the seabed. I’ve seen them in Spain & France, and they’re slowly popping up in Greece too. They cost a little more than anchoring for free, but they save the meadows and often give you peace of mind that you’re secure and legal.

Some cruisers complain about losing the “freedom to anchor anywhere,” but I see it differently. If we want to keep those clear blue bays, we have to look after what’s under the water too.

Why It Matters to Me

For me, rules that protect the ocean have never been a hassle. I feel a deep love for the sea and everything that lives in it, so I always welcomed these measures. The more I sailed in the Med, the more I appreciated how Posidonia rules protect the bays we all enjoy.

So next time you’re about to drop anchor in the Med, take a second look at the color of the water. If it’s dark, it’s probably Posidonia. Shift a little until you find the sand, or pick up an eco-mooring if one’s available. It’s a small change, but together it makes a big difference.

👉 If you want more Med cruising advice, have a look at our guide to Best Marinas in Greece for Liveaboards or our breakdown of the Cost of Living on a Boat in Greece.

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