Posidonia in the Balearics: where you can anchor and how to avoid a fine
By Luis Carvajal · Updated 1 October 2026
In short: in the Balearic Islands anchoring on Posidonia seagrass is forbidden as a general rule. Over the meadow you may only moor to authorised buoys. Anchor in the light patches of sand, check where your anchor has landed and, if in doubt, look at the official map or call the Posidonia phone line.
What it is and why it is protected
Posidonia oceanica is a marine plant, not an alga, found only in the Mediterranean. Its meadows are the dark patches you see from the boat. They oxygenate the water, keep it clear, shelter fish and slow the erosion of beaches. They grow very slowly, a few centimetres a year, so what an anchor rips out takes decades to recover.
What the rules say
Decree 25/2018 of the Balearic government, on Posidonia conservation, is clear in its article 7:
- Anchoring boats on Posidonia is forbidden as a general rule.
- Over the meadow, mooring is only allowed to authorised low-impact systems, meaning buoys or buoy fields.
We found no exemptions by boat length or by depth: it applies to every boat.
An important detail: the government states that its mapping is for information. Fines are not based on what the map says but on where your anchor actually is.
What can happen
Anchoring on Posidonia is an environmental offence. Fines fall under natural-areas law, both Balearic (Law 5/2005) and Spanish national (Law 42/2007), and range from hundreds of euros for minor cases to five- and six-figure sums for serious ones. The actual amount depends on each case.
In season, from June to early October, the government's Posidonia Surveillance Service patrols the coves with around twenty boats. Its wardens inform you and ask you to move; formal reports are handled by environmental officers and other authorities.
How to tell if there is seagrass below
- Look at the water. Sand shows light and turquoise; the meadow, dark. Find a patch of sand big enough for the boat to swing, not just for the anchor.
- Check the anchor with a mask, or from the bow when the water allows. An anchor on sand with the chain dragging over the meadow as the boat swings does damage too.
- Check the official map: the government's Posidonia viewer (IDEIB) and the Atlas Posidonia site.
- Ask: the government runs a Posidonia phone line, +34 617 975 172, by call or text, during the season.
Buoy fields
In coves where the meadow covers almost the whole bottom, PortsIB lays seasonal eco-buoy fields from 1 June to 30 September (extendable to 15 October). There are buoys for boats up to 8, 12, 15, 20 and 25 metres, booked at reservas.portsib.es.
Where they are, island by island, is in our guides to Mallorca, Menorca and Ibiza and Formentera.
How Offing helps
Offing carries the Balearic government's official Posidonia mapping. Tap a spot on the chart and, if it is meadow, it warns you. Areas you download in port take the seagrass with them, so the warning works in the cove even with no signal. It marks marine reserves too.
Like the mapping itself, the warning is indicative: the map and the real bottom can differ. It warns; it does not authorise. You make the final call, looking at the bottom.
Offing
Balearic seagrass on the chart, offline. Plus depth, sea and wind for any spot you tap, the official forecast and a logbook that writes itself. One payment.
Sources
- Decree 25/2018 on the conservation of Posidonia oceanica in the Balearic Islands (Spanish)
- Government of the Balearic Islands, anchoring and Posidonia (Spanish)
- Government of the Balearic Islands, Posidonia Surveillance Service (Spanish)
- BOE, Law 5/2005 and Law 42/2007 (Spanish)
- Government of the Balearic Islands, PortsIB buoy fields (Spanish)