Anchoring rules: Posidonia, marine reserves, buoy fields and black water

Spanish waters protect Posidonia seagrass and marine reserves. Know where anchoring is banned, how buoy fields work, and why black water stays aboard.

Updated 24 Oct 2026 2 min read

Key points

Posidonia oceanica meadows are protected. The Balearics ban anchoring on them by decree (25/2018).
Marine reserves such as the Illes Medes and Cabrera National Park restrict anchoring and use buoys.
Use your holding tank and pump out ashore. Discharge near the coast is prohibited in many areas.

Posidonia

Posidonia oceanica is a seagrass that forms meadows on the sandy seabed of the Mediterranean. It produces oxygen, shelters fish and stabilises the seabed, and it grows very slowly. An anchor and chain destroy it. In the Balearics, Decree 25/2018 prohibits anchoring on Posidonia meadows. Catalonia and the French coast also restrict anchoring in many areas.

How to anchor without harming it

Anchor on bare sand, which looks pale in clear water. Posidonia looks dark.
Use an app or official map that shows the meadows.
Look from the bow before you drop. If in doubt, go elsewhere.
Go to the sand, not the edge of the meadow, so a dragging anchor does not reach it.

Marine reserves and parks

Cabrera Archipelago National Park (Mallorca) needs prior authorisation and offers moorings.
Illes Medes (L'Estartit) marine reserve restricts anchoring and activities.
Cap de Creus Natural Park has restricted zones.
Ses Salines d'Eivissa i Formentera Natural Park has strict Posidonia protection.

Rules change between seasons and zones. Check the park's website before you go, and check for permit deadlines.

Buoy fields

Many popular bays use seasonal moorings to keep boats off the seabed. You pick up a buoy and pay a fee, often through a booking system or on arrival. Fees and booking rules differ between operators. Arrive early on summer weekends, because places fill up.

Black water

Untreated sewage damages water quality in closed bays and reserves. Many protected areas prohibit all discharge, and the rules elsewhere vary with distance from the shore and the local authority. The simple practice is to use the holding tank and the marina pump-out. See Fuel tanks, gas installation, plumbing and holding tanks. Grey water from sinks should use biodegradable soap.

Fines

Authorities patrol in summer, and fines for anchoring on protected seabed can be large. Check the current penalty for the zone.

Also useful at step 6 Cruising grounds from Barcelona: Costa Brava, Balearics, South of France

General information, not legal, tax or financial advice. Rules change; check your own case with a professional or ask us.