BOAT-COMPARATOR Guide
Anchoring on Posidonia Seagrass: What the Law Says in the Mediterranean
Fines, no-anchor zones, eco-friendly mooring buoys: the Mediterranean's posidonia seagrass anchoring rules explained simply for renters.
Posidonia is not seaweed but a flowering plant, unique to the Mediterranean, forming vast underwater meadows between the surface and 30-40 metres deep. These meadows shelter much of the basin's marine life and grow extremely slowly — an anchor that tears one up takes decades to heal. That is why anchoring on it is now strictly regulated, even for an ordinary rental boat.
What the regulation says
Under the Mediterranean maritime prefect's framework order (no. 123/2019), anchoring on posidonia meadows is banned for vessels over 24 metres in protected zones. Decree no. 2023-1000 of 27 October 2023 tightened the rule further, lowering the threshold to certain vessels over 8 metres in the most sensitive areas and making equipped mooring zones (ZMEL) mandatory in the coastal towns concerned.
The penalties involved
Anchoring in a banned zone carries a fifth-class fine, around €1,500, on top of which ecological-damage compensation exceeding €100,000 can apply in the most serious cases — the maximum fines set out in the texts reach €150,000. These figures mostly concern large vessels, but the underlying rule is the same for everyone: never an anchor on the meadow.
ZMEL zones: the stress-free way to anchor
On the busiest waters, equipped mooring zones (ZMEL) offer buoys attached to eco-friendly anchors — screw or helical anchors driven into the sand — which keep the boat from ever touching the meadow. Picking up one of these buoys, where available, remains the simplest way to anchor without a second thought.
What to check as a renter
Operators generally hand over a map of the areas to avoid, and marine charting apps show the seabed type before you drop anchor. In protected waters such as the Hyères roadstead and Port-Cros, or in the Balearics, aim for clearly visible sand or an organised buoy — our marine protected areas guide covers the other rules to know before anchoring.
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